Computing Concepts Grade IX
Computer –
Computer is an electronic and a digital device capable of accepting, storing,
processing and retrieving the data given by the user to generate information.
Computer works on the principle of
Input Process Output
The general purpose for using a
computer is to process data and generate information.
Characteristics of a Computer
a)
Storage
b) Speed
c)
Accuracy
d)
Automatic
e)
Versatility
f)
Diligence
Storage – Computers can store large volumes
of data and information in its memory. It stores the information in terms of
bits and bytes which are represented by 0’s and 1’s.
Speed –
The rate of doing work by a computer is very high because it works in seconds
which are measured in terms of Hertz
(Hz) and Mega hertz (MHz), Giga hertz (GHz).
Accuracy
– A computer is capable of performing tasks accurately or without making any
mistakes unless the instructions given by the user itself is wrong. ( the term
associated with this phenomena is called
garbage in garbage out GIGO )
Automatic-
Once we give the appropriate instruction a computer can perform the operation
automatically. It carries on with the task independently and continuously.
Versatility –
Computer is a versatile machine so it can perform various tasks such as
mathematical and logical operations as well as textual manipulations etc.
Diligence -
A computer is capable of performing a task over a number of times without
making any mistakes repeatedly and consistently.
Limitations of a Computer – The major limitation of a computer is that in order to
perform or carry out a task it needs specific instructions, it simply cannot
work on its own.
Why do we need a computer?
We need a computer for:
Ø Storing data
Ø Processing data
Ø Generating information
Ø Communication
Ø Using multimedia etc.
Information on bits and bytes:
0 or 1 = a bit
4 bits = a nibble
8 bits = 1 byte
1024 byte = 1 Kilo byte (KB)
1024 KB = 1 Mega byte (MB)
1024 MB = 1 Giga byte (GB)
1024 GB = 1 Tera byte (TB)
1024 TB = 1 Peta byte (PT)
Computer System
Computer system is an integration
(combination) of hardware and software.
From the physical aspect, a computer
system consists of :
a) Input
unit
b)
Processing unit including main memory
c)
Secondary storage
d)
Output unit
Which are controlled and managed by
the system software.
Input
– Data and instructions given by the user to the computer is referred as input
Input Unit/Devices – Input devices are the medium by which the user gives data
and instructions to the computer.
Input devices converts input
information to a suitable form acceptable to a computer.
Common examples of input devices are
keyboard, mouse scanner etc.
Why does a computer need input devices?
Computer basically works on the
input (data and instructions) given by the user so in order to receive data and
instruction a computer needs input devices like keyboard etc.
Keyboard-
It is an essential input device, the data and instructions are entered into the
computers memory through keyboard.
Keyboard encoder- Keyboard encoder is a circuit that generates binary codes
whenever a key is pressed on the keyboard. The binary code is sent to the
computer.
Mouse – Mouse is an input device used for pointing, clicking and
dragging icons etc.
Central Processing Unit- The function of CPU is to store the temporary current data
and execute programs. The CPU also controls the operations of input and output
devices and the memory. Under the control of CPU, data and programs are stored
in the memory and displayed on the monitor (screen) or printed on the printer.
Major sections of CPU:
·
Arithmetic Logic Unit (ALU)
·
Primary Memory
·
Control Unit (CU)
Arithmetic Logic Unit: The Arithmetic Logic Unit (ALU) performs all the
arithmetic and logical operations. The arithmetic computations include
addition, subtraction, multiplication and division while logical operation
includes comparisons.
Control Unit: It generates control signals necessary for the execution
of instruction. In fact, it generates control signals which are necessary for
the operations of different parts of the CPU, memory and input/output (I/O)devices. It controls the
entire operation of a computer.
Semiconductor Memories- semiconductor memories are used as the main memory. They
can be accessed randomly, so the access time taken is less and they are fast
type of memory.
The semiconductor memories are
classified into
a)
Random Access Memory (RAM)
b) Read
Only Memory (ROM)
Primary or main memory- The RAM and ROM are considered the primary memory of the
computer system.
Note: The primary memory (typically
RAM) stores the program to be executed, holds the input data that is to be processed
and the intermediate results of any calculation when the processing is being
done. When we enter data and program into the computer , the data and program
are first stored in primary memory under thee control of control unit.
RAM - Random Access Memory:
Random
Access Memory (RAM)is the best known form of computer memory. The Read and
write (R/W) memory of a computer is called RAM. The User can write information
to it and read information from it.
The
RAM is a volatile memory, it
means information written to it can be accessed as long as power is on. As soon
as the power is off, it can not be accessed. So RAM holds data and processing
instructions temporarily until the CPU needs it.
Types of RAM
i)
Static RAM (SRAM)
ii)
Dynamic RAM (DRAM)
Static RAM (SRAM) – A static RAM retains stored data , information and
programs as long as the power supply is on. The SRAM’s have higher speed as
compared to dynamic RAM.
Dynamic RAM
(DRAM)- A dynamic RAM loses the stored information in a very short time even
though the power supply is on. Thus DRAM’s have to be refreshed from time to
time. They can be used whenever we need larger memory capacity.
ROM - Read Only Memory:
Read only memory (ROM) is an example
of nonvolatile memory. ROM is a class of storage medium used in
computers and other electronic devices. Read Only Memory (ROM), also known as firmware,
is an integrated circuit programmed with specific data when it is manufactured.
The instructions for starting the computer are housed on Read only memory chip.
Types of ROM :
PROM: This stands for Programmable
Read Only Memory. It is a semiconductor memory which can only have data
written to it once - the data written to it is permanent. These
memories are bought in a blank format and they are programmed using a special PROM
programmer.
EPROM: This is an Erasable Programmable
Read Only Memory. This form of semiconductor memory can be
programmed and then erased at a later time. This is normally achieved by
exposing the silicon to ultraviolet light.
EEPROM: This is an Electrically Erasable
Programmable Read Only Memory. Data can be written to it and it can be erased
using an electrical voltage. This is typically applied to an erase pin
on the chip. Like other types of PROM, EEPROM retains the contents of the
memory even when the power is turned off. Also like other types of ROM, EEPROM
is not as fast as RAM.
Note:
Memory :
A device for storing digital information that is fabricated by using integrated
circuit technology. Also known as integrated-circuit memory; large-scale
integrated memory; memory chip; semiconductor storage; transistor memory.
There is a large variety of types of
ROM and RAM that are available. These arise from the variety of applications
and also
the number of technologies available. This means that there is a large number of abbreviations or
acronyms and categories for memories ranging from Flash to MRAM, PROM to EEPROM,
and many more.
Differences between
RAM and ROM:
·
A ROM chip does not require a
constant source of power to retain the information stored on it, whereas a RAM
chip does require a constant source of power to retain the information.
·
A user can read and write in RAM but can only read or access the contents of
ROM.
Cache Memory- The cache memory
stores the program (or its part) currently being executed or which may be
executed within a short period of time. The cache memory also stores temporary
data that the CPU may frequently require for manipulation.
It
acts as a high speed buffer between CPU and main memory and is used to
temporary store very active data and action during processing since the cache
memory is faster then main memory, the processing speed is increased by making
the data and instructions needed in current processing available in cache. The
cache memory is very expensive and hence is limited in capacity.
Secondary/ Auxiliary/Backup Memory:
The common backup storage used are:
·
Hard-disk
·
CD/DVD ROMs
·
Pen drive
Why do we need a backup memory?
The primary memory i.e. RAM of the
computer is of volatile nature the data stored in RAM gets erased as soon as
the power is switched off. So, in order to save data and information
permanently backup up storage like hard disk, pen drive etc. are needed.
Differences between primary and secondary memory:
·
The primary memory is embedded with two types of memory technologies;
they are the RAM (Random Access Memory) and ROM (Read Only Memory). The
secondary memory is accessible in the form of Mass storage devices such as hard
disk, memory chips, Pen drive, CD and DVD etc.
·
Primary memory is volatile in nature, while secondary memory is
non volatile. The information that is stored in the primary memory cannot be
retained when the power is turned off. In case of secondary memory, the
information can be retrieved even if the power is turned off because the data
will not be destructed until and unless the user erases it.
Output-
The result of processed data is called as output which is often referred as information.
Output Unit/Devices- The output devices are the medium through which a computer
displays the input data or generates the result of processing.
Example: Monitor, Printer, Speaker
etc.
Processing
– The systematic manipulation of data by the computer based on user’s
instruction is called processing.
Hardware Concept
Hardware- The physical components of
a computer system are called hardware.
Common examples of hardware :
Monitor, keyboard, Mouse, Printer etc.
Motherboard-
Motherboard is a rectangular piece of fiberglass plate on which all the
electronic components are mounted. Very thin parallel lines of metal on the
surface of line fiber glass connect pins from one component to another forming
the computers electronic circuits. This is also called a Printed Circuit Board
or PCB board.
Secondary/Backup/ Auxiliary Memory:
Secondary memory is used for storing
large volumes of data. There are many different types of secondary memory that
are being used . The common ones are magnetic disk, e.g. hard-disk, optical
disk (CD/DVD), pen drive etc.
Magnetic tape-
Magnetic tape is a secondary sequential storage medium, it is used as an input
storage medium for high speed large volume storage. Its data density is high
and transfer rate is comparatively fast. Data are recorded in the magnetic tape
in the form of small magnetized spots. It utilizes the BCD ( Binary Coded
Decimal) system in recording digits, letters and other characters.
Advantages of Magnetic Tape
a)
Magnetic tape can be erased and reused.
b) Mass
data storage in magnetic tape is cheaper
Disadvantages of Magnetic Tape
a) As
the data in the magnetic tape is accessed sequentially it is slow to access
selected data.
b)
Magnetic tapes can be adversely affected by dust, heat and humidity.
Magnetic Disks-
Magnetic disks are the most popular
direct access I/O ( input/output) and online storage medium. Magnetic disks
used as storage medium are commonly available in the following forms:
a)
Floppy disk b) Hard disk
Hard-disk-
Hard disks are commonly used as a secondary storage media in microcomputers and
large computers. A hard-disk is made of metallic disk coated with metallic
oxide on both sides. The hard disk is permanently fixed in a drive unit case of
microcomputers. To increase the storing capacity several disks or platters are
packed together and mounted on a common drive to form a disk pack.
Optical storage: a) CD-ROM b) DVD-ROM
CD-ROM
– The CD_ROM stands for compact disk read only memory. It is an optical disk,
which enables pre-recorded data to be read.
Advantages of CD-ROM
i)
Mass storage media for text, sound, graphics video etc.
ii)
Reliable and economic storage media.
Disadvantages of CD-ROM
Data access time (time taken to read
data) is longer as compared to hard disks.
CD-RW and WORM
CD-RW ( Compact Disk Re-Writable)
disks on which you can record and erase as many times as you want , they are
also known as CD erasable disk.
WORM mans an empty CD, in which you
can write once and read many times.
DVD-ROM-
DVD (digital versatile disk) are different from the conventional CD-ROMs. This
is also a new kind of mass data storing device. DVD can hold 4.7GB of
information.
Pen Drive-
A pen drive though small in size is capable of storing large volumes of data.
It is a reliable form of storing and transporting data.
Bar code-
A bar code is an identification code appearing on retail product packaging. The
code consists of light and dark lines which are used to represent data.
Bar code reader-
A bar code consists of bar i.e. lines of varying thickness and spacing between
them. The bar code have to be scanned and decoded to get its value, the device
which is used for scanning the bar code is called bar code reader.
A bar code reader reads the bar code
and converts them to electrical pulses which are sent to the computer for
processing.
Joystick-
A joystick is a pointing device used to move the cursor on the monitor
(screen). It can also be used to choose the options of menu oriented
applications especially games.
Track ball-
Track balls are popular pointing devices for the portable computers or laptops.
Touch pad-
A touch pad is also a pointing device for portable computers. By moving your
finger or other objects along the pad, you can move the pointer on the monitor.
Scanner-
A scanner or a digitizer is an input device that can be moved over a drawing or
photograph to convert it into digital data.
Types of scanner:
i)
Optical Character Reader (OCR)
ii)
Optical Mark Reader (OMR)
Optical Character Reader (OCR)- An OCR is a direct entry input device. It can detect
alphanumeric characters printed on any paper.
The scanning capacity of OCR is
several thousand characters per second. It is mostly used at department stores
to convert the retail tags and send the data to the computer for processing or
billing.
Magnetic Ink Character Reader- MICR is a direct entry input device, which reads the
characters that have been printed in magnetic ink. Magnetic ink is a special type of ink
containing iron oxide particles, which is used to write characters.
MICR are popularly used in banks for
processing cheques, credit card etc. MICR has the capacity to process about 2600
cheques per minute.
Microphone-
Microphone is an input device, which converts a person’s speech into digital
form. It is also called headphone. These
input devices, when combined with appropriate software form voice recognition
system.
Digital camera-
Digital camera is also an input device where one can store images. Using this
camera one can take multiple photos and store them into its memory.
Output devices:
Monitor-A
monitor is an electronic
visual display
for computers. The monitor comprises the display
device, circuitry and an enclosure. The display
device in modern monitors is typically a thin film transistor liquid crystal display (TFT-LCD) thin panel, while older
monitors use a cathode ray tube (CRT).
Monitor is an output device the
output generated by a monitor is called as the soft output.
Note: The terms VGA, SVGA, XGA,
SXGA, UXGA etc., all relate to the resolution a monitor supports.
Pixel-
Pixel is a picture element on the screen (monitor).
Adapter:
The display on the monitor is controlled by an electronic circuit known as
adapter
Printers-Printers
are the most common output devices. The printer provides information in a
permanent readable form, known as hard copy output.
Types of printers:
i)
Impact printers
ii)
Non-impact printers
Impact Printers-
Impact printers are like typewriters. The characters are formed i.e. printed by physical striking the type
device against an inked ribbon.
Examples of Impact Printers: Dot
matrix printers, drum printers etc.
Non Impact Printers- A non impact printer does not strike the paper to form
(i.e. print) the characters. The characters are formed by electrostatic ,
inkjet or laser beam technology.
The characters formed in different
technologies are as follows:
Name of the Printer Technology
|
Inkjet
printer |
By
using ink spray |
|
Laser
printer |
By
using laser beam |
Further classification of printers:
a)
Character printer – Prints one character of text at a time.
b) Line
printer- Prints one line of the text at a time.
c) Page
printer- Prints one page of the text at a time.
Speaker – As and when necessary, the computer produces
sounds as an output during the time it is being used. It is made possible due
to the speaker, hence it is an output device.
Graph Plotter- A
plotter is a printer like output device used for producing hard copy outputs of
charts, maps, drawings etc.
Types of plotters
i)
Pen plotter
ii)
Electrostatic plotter
iii)
Dot matrix plotter
Pen plotter-
The pen plotter have one or more pens. It can produce the graphic in different
colors and we can shade the selected portion of the graphic as required.
The pen plotters are of two type
flatbed plotter and drum plotter.
Flatbed plotter-
In a flatbed plotter, the pens move and the paper is fixed.
Drum plotter-
In a drum plotter pens are stable and the paper is moved on the drum.
Electrostatic plotter- This type of plotter works without a pen. They work on
similar principle as the electrostatic type of non impact printer.
Dot- matrix plotters- It works on the same principle a the impact type dot
matrix printers. This type of plotters can not produce the graphics in
different colors. The resolution (quality of graphics) of dot matrix printers
are better than the pen type plotters.
Software-
The set of programs that controls and manages the computer hardware and does
various user assigned task is referred as software.
Types of software
1)
System Software (which includes)
i) Operating System
ii) Utility programs
iii) Language processors
2)
Application Software
System Software-
System software are the general programs written for the system which provide
the environment to facilitate the writing of application software. In fact the
software required to execute user’s program is known as system software.
Operating System- An operating system (OS) is an organized set or collection
of software programs that controls the overall operation of the computer
system.
Examples of operating system:
MS-DOS
WINDOWS-XP/7/8
UNIX
LINUX etc.
Functions of operating system:
a)
Supervision of the overall operation of the computer system
b)
Providing various support functions program to the user.
Utility Program-
These are software tools which help users in developing, writing, debugging and
documenting programs.
The utility program can be
categorized into
a) File
management utilities- These are the programs to help the user in copying,
erasing, renaming and printing files.
b) Program
development utilities- They are programs to help users to write and test
programs
Language Processors- The programs which translates the program written in a
programming language by the user into an executable program is known as
language processor.
The program translated by the
language processor is understood by the hardware of the computer.
Example of language processor are
assembler, compiler and interpreter.
Assembler-
A program which translates an assembly language program into machine language
is called a assembler.
Compiler-
A compiler is a program which translates a program written in a high level
language into a language that can be understood by the computer. The compiler
translates whole program at a time.
Interpreter-
Interpreter is a program which translates the statement of a high level
language into machine codes. It translates one statement at a time.
Computer language:
An artificial language designed to
convey instruction to a computer is known as a computer language.
Types of Programming languages:
- High level Programming Language
(QBASIC)
- Middle level Programming
Language (C )
- Low level programming Language
( Assembly Language)
- Machine Language ( instructions
written using 0’s and 1’s)
High level language- The programming language that is independent of the
computer hardware is referred as a high level language. High level language is
problem oriented rather than computer oriented. The programmer does not need
the knowledge of the architecture of the computer that is being used.
Examples of high level languages:
BASIC, COBOL, PASCAL etc.
Advantages of high level language:
i)
The programs written in one type of computer equally runs on the next i.e. the
programs are portable.
ii)
Programs of high level languages are easy to write modify and debug.
Classification of High Level Programming Language
a)
Scientific Language (PASCAL )
b)
Commercial Language (COBOL )
c)
Artificial Intelligence Language (LISP)
d)
Special Purpose Language (SNOBOL)
Low level language- A language in which each statement is directly translated
into a single machine code is a low level language. Assembly language is an
example of a low level language.
Assembly Language – A program written in mnemonics is known as assembly
language program.
The meaningful and easily
remember-able alphanumeric symbols are called mnemonics.
Machine Language- The language in which a computer works is called a machine
language.
A program written in the form of 0’s
and 1’s is called a machine language program.
Demerits of machine language program:
i)
Program writing is difficult and tedious
ii)
Chances of errors in writing programs are very high
iii)
Debugging of errors in the program is difficult
iv)
Program entry is slow.
Application software- Application software are the programs used for solving or
doing tasks of specific (particular)
nature.
Examples of application software:
a)
MS-WORD (WORD PROCESSOR)
b)
MS-EXCEL (SPREADSHEET)
c)
MS-ACCESS (DBMS)
Tailored made software- Tailor made software is software that is made to the specifications
of a client. In other words it is custom made, bespoke, or 'tailored' to
address a specific need.
Example : Result processing software
for schools.
Packaged software- A packaged software is a generalized form of application
programs meant for solving tasks of similar and varied nature for example
MS-OFFICE ,it is a package containing word-processor, spreadsheet, database
management etc.
SUCHANA PRABIDHI NITI 2052 ( IT
POLICY 2002 )
Vision -
To place Nepal on the global map of information technology within next five
years.
According to the policy, Nepal will
be recognized or known by the world as one of the countries going hand in hand
with information technology, producing human resources (IT experts) as such,
software, hardware etc.
Objectives:
The IT policy shall formulate to
achieve the following objectives:
·
To create knowledge based society.
·
To create job opportunities for the people.
·
To establish knowledge based industries.
Information Technology (IT) Policy
To fulfill the objectives, the
following shall be followed:
·
To include computer education in the curriculum starting from the school level
and broaden its scope.
·
To use information technology to promote e-commerce, e-health, e-education etc.
Among others and to transform technology in the rural areas.
·
To establish a national information technology center.
Institutional Management
NITDC-
National Information Technology development Committee (NITDC) was established
in 2003 AD to develop information technology in the country.
National Information Technology Center (NITC)- To develop and expand the areas of
information technology, to revise and update, to supervise and monitor the
yearly progress and to solve the problems regarding IT, an organization called
NITC has been established in 2003 AD. NITC is working under NITDC.
National Information Co-ordination Committee (NITCC) – Regarding information technology
to develop the curriculum to develop manpower, to fix standard and levels, to
organize the research works and to co-ordinate between private institutes and
governmental organizations for this purpose NITCC has been formed in2003 AD.
Legislation-
Nepal government will design, update and implement the cyber laws from time to
time as per national and international situation. The law will be related to
e-banking, digital signature, software piracy, data protection by encryption,
copyright protection and privacy protection act etc.
Updating the IT policy:
Nepal government will supervise the
running of cyber law from time to time and rewrite them to update. In every two
alternate years continuously , it will be updated.
Introduction to HTML
Computer Network – Connection between two or more computer is called
computer network.
Internet-
Global connection of interconnected computer networks is called Internet.
History of HTML
– Hyper Text Markup Language (HTML) came into existance in 1990, the
development of HTML was initiated by Tim Berners Lee and later taken over by
Dan Conolly and Dave Ragett and a team of other volunteers.
HTML
can be referred as a subset of SGML ( Standard Generalised Markup
Language) which was developed by International Standard Organization (ISO) and
was used by US DoD ( United States Department of Defense )
HTML has been in use on the www
(world wide web ) since its origin in 1990, it has gained popularity to the
extent of becoming standard on the world wide web.
HTML
– HTML stands for Hyper Text Markup Language. It is a platform independent (
hardware independent ) simple text formatting language used to create hypertext
documents.
Hypertext
– Codes written in HTML is called hypertext. Hypertext is one method of
presenting information in which certain items are highlighted, by selecting the
highlighted text, one can obtain information on same topic.
Hyperlink
– HTML is a versatile language that allows the creation of hypertext links also
known as hyperlink.
Pages on a website are all linked
together, one can move from one page to another page by clicking on words or
pictures.
Webpage
– The information on web is contained in millions of computer documents called
webpage. (collection of hypertext documents )
Web site-
a web site is a group of web pages containing various information created by a
person or organization.
URL (
Universal / Uniform Resource Locater ) – URL means a web addressing scheme that
spells out the exact location of a net resource.
IP (Internet Protocol ) address – IP address is an identifier for a particular machine on a
particular network. It is a part of a system to identify computers on the
Internet. Each computer is assigned a unique IP address and it is referred to
as IP number and Internet Address.
Web-browser
– Web browser is a client (application software ) that allows to display and
interact with the hypertext document ( web pages).
Example of web browsers are: Internet Explorer, Mozilla Firefox, Google
Chrome, Opera etc.
Web server-
Web server is a place (computer) where web pages reside (store). It is actually
a program that respond, requests from the web browser to retrieve resources.
Home page
– homepage is the first hypertext document that gets loaded whenever you follow
a link to a web server.
Homepage is an introductory page
containing information about the web page or web site.
HTML tags
– AN HTML instruction is called a tag. Tags usually come in pairs an opening
tag and a closing tag.
For example : <B>
HELLO </B>
Opening Tag Closing Tag
Types of tags:
HTML tags can be classified into two
types:
a) Paired
tags
b)
Singular or empty tags
Paired Tag- A tag is said to be a paired tag if it, along
with a companion tag flanks the text. Paired tags are also called container
tags.
For example : <U> HELLO </U>
Opening Tag Closing Tag
Singular or Empty Tag – Singular tags are also called empty tags. These types of
tags does not require any companion tag.
For example : <BR> HELLO
Point to remember;
·
HTML tags are usually written in upper case letters and are enclosed within
less than (<) and greater than (>) symbols, which are referred by the
HTML scriptn writers as brackets.
·
Most HTML tags consist of two parts, an opening tag and a closing tag. The
closing tags are just like opening tags except that the tag name starts with a
slash (/).
Attributes –
Some types of tag need extra information which is called the tags “attribute”
for example an IMG tag need the filename o the image and size of the image and
how the browser should align the image with respect to the sorrounding text.
Basic Structure
(elements of HTML document)
Tags given below must appear at the
top and at the bottom of a document.
<HTML>
<HEAD>
<TITLE> PAGE TITLE
</TITLE>
</HEAD>
|
CONTENTS |
<BODY>
-----------------------------
-------------------------------------------
-------------------------------------------
</BODY>
</HTML>
HTML
– HTML document has a typical kind of structure and it is essential to know the
basic HTML tags. The entire web page is enclosed within <HTML> and </HTML> tags,
<HTML> is opening tag and </HTML> is the closing tag.
Header –
The header tag <HEAD> and </HEAD> surround the introductory
material such as the title of the page. It is a part of the HTML document,
which actually provides information about the document to the browser.
TITLE-
The TITLE tag helps you to give the title of the web page, which is displayed
on the title bar of the browser window. You can type the text between a
<TITLE> and</TITLE>. These
tags are used in between header tags.
BODY
– All information that are to be displayed on the browser screen is called body
section. The body section start with a <BODY> and ends with a
</BODY> tag.
Background –
The background attribute specifies the name of the GIF image file that will be
used as a background of the page.
BGCOLOR –
to change the default background color to whatever color is specified with this attribute, the
color can be specified by name or by its equivalent hexadecimal number.
Example <BODY BGCOLOR =
“GREEN”>
TEXT –
To change the body text color from its default value to the color specified
with the attribute.
Margin (left/ right) – This attribute is
used to specify the margin of the web page. The value is specified to this
attribute in terms of pixels.
Link –
This defines the color in which to display hyper text links which have not yet been visited.
VLINK- This defines the color for links which have
previously been visited.
ALINK-
This defines the color of the link as you actually click in with the mouse.
<P> tag
– This tag is used for creating paragraph break. Paragraph break separates a
line in text material.
<PALIGN>
tag – It is used for alignment ( position ) of the text in a document.
Examples of alignment are – left,
center,right.
Examples of <P> and < P
ALIGN > tags:
<HTML>
<HEAD>
<TITLE> OUR PAGE
</TITLE>
</HEAD>
<BODY>
<P>
<P ALIGN = LEFT > 6 BOYS </P>
<P ALIGN = RIGHTT > 4 GIRLS </P>
<P ALIGN = LEFT > OF CLASS IX </P>
<P> SUBJECTS WE STUDY
< P ALIGN = CENTER> NEPALI,
MATHS, COMPUTER ETC.
</P>
</BODY>
</HTML>
Using FONT and its attributes: - this tag is used to
specify the Font and its formatting options regarding its type, size and color.
It takes some attributes, which are as follows :
|
Attributes |
Description |
|
FACE |
To change the font type of the
text |
|
COLOR |
TO change the color of the text .
the color an be specified by NAME as “ light sky blue” or in hexadecimal
number as “#87CEFA” |
|
SIZE |
To change the size of the text .
The size can take any value from 1 to 7. The default size is 3 |
Example of combining tags:
<FONT FACE = “ARIAL”><FONT
SIZE=”4”><FONT COLOR=”GREEN”> HIMS
</FONT></FONT></FONT>
Using Font Styles
These font styles tags help to
change the appearance of the text in an HTML document. It is very useful to
prepare an attractive text. It is a paired tag, it needs both starting and an
ending tag. Popularly used formatting tags are :
Bold <B> - It helps to have
bold format to the text.
Italic <I> - It helps to have
italic format to the text.
Underline <U> - It helps to
underline the text.
Center <CENTER> - It helps to
center the text.
Superscript <SUP> - It helps
the text to have superscript effect (move the text up)
Subscript <SUB> - It helps the
text to have subscript effect ( move the text down ).
Line Breaks
– The <BR> tag is used for inserting a line break. The text that follows
the <BR> will be displayed in the next line. This is an empty tag, which
means that no closing tag is required for
<BR>.
Horizontal Ruler – The horizontal ruler tag <HR> creates the
horizontal line in HTML documents to help add structure to the web page. The
horizontal ruler can be used to divide sections of the document.
Example :<HR SIZE = 10 >
|
Attributes |
Description |
|
ALIGN |
Helps to set vertical alignment
(left, right, center ) of the ruler. |
|
SIZE |
To set the height of the ruler |
|
WIDTH |
To set the width of the ruler |
|
NOSHADE |
To create the ruler without shadow |
Example of horizontal ruler tag :
<HR ALIGN CENTER> WE
<HR SIZE =8 > THE STUDENTS OF
<HR WIDTH =20%> EURO
< HR NOSHADE> WELCOME YOU ALL
Heading Tags
– To introduce different sections on the webpage, headings are used. Heading
helps visitors to find information in a site quickly. Heading basically helps
to change the font style of a text.
There are six sizes of headings.
Level 1 is the biggest and level 6 is the smallest.
Level 1,2,and 3 are usually used for
titles.
Example:
<H1> EURO</H1>
<H2> EURO</H2>
<H3> EURO</H3>
<H4> EURO</H4>
<H5>EURO</H5>
<H6> EURO</H6>
Marquee tag - It allows to move the text in the browser
screen. It highlights the scrolling text across the page.
Marquee attributes:
BEHAVIOR = ALTERNATE, SCROLL or
SLIDE
|
ALTERNATE |
It helps the text bounce forward
and back within the marquee |
|
SCROLL |
Helps the text start completely
off one side of the screen and then start again |
|
SLIDE |
It helps the text start completely
off on the screen and stop the marquee text. |
|
BGCOLOR |
To specify the background color
for the marquee |
|
DIRECTION |
To specify the direction in which
you want to scroll the text ( lift, right up, down) |
Example of Marquee tag:
<MARQUEE> HIMS
</MARQUEE>
<MARQUEE BEHAVIOR = ALTERNATE> EURO </MARQUEE>
<MARQUEE BEHAVIOR = SLIDE> EURO </MARQUEE>
<MARQUEE BEHAVIOR = SCROLL> EURO</MARQUEE>
<MARQUEE BEHAVIOR = ALTERNATE
DIRECTION = UP> HIMS </MARQUEE>
<MARQUEE BEHAVIOR = SLIDE
DIRECTION = DOWN BGCOLOR = “GREEN”> HIMS </MARQUEE>
Anchor
– the section between <A> and the
</A> of the body is called an anchor. When you click a link or
code, the browser loads the file or document given by the links corresponding
URL references.
Linking tag
– Links are created in the web page by using the link tags <A> and
</A>. Link is used to provide a connection to another part of a page, to
another page or to another web page. The text or an image that provides such
linkage is called hyperlink or hypertext.
HREF = “ …………….. “
HREF = “……………… “ is an example of an
attribute. It defines the URL of the destination of the anchor. In HREF you can
add the tag to provide an option or additional information. The HREF attribute
specifies what the link will link to.
|
Body of anchor |
|
Defines URL Destination of anchor |
|
URL RESOURCE |
Example :<A HREF =
“http://www.yahoo.com “> GOTO YAHOO </A>
IMG tag
– The image tag is used to insert images ( picture ) into HTML document that
should be displayed in the browser screen. The IMG tag dose not haven end tag.
Atributes of IMG tag:
SRC
– It defines the name of the file in which the image is to be found.
WIDTH
– To specify the width of the image in pixels.
HEIGHT
– To specify the height of the image in pixels.
ALIGN –
To wrap the text around the image file.
ALT
– To display the image.
Working with table – A table is a two dimensional matrix, consisting of rows
and columns. They make a comparative analysis more understandable. HTML tables
are composed row by row. A row is indicated with the <TR> (table row) tag
and the data is seperated with either the <TH> (table header) or
<TD>( table data ) tags.
<TR> tag can be compared to a
line break, signalling that following data starts a new table.
A table consists of a number of HTML
structures nested inside one another.
<TABLE>
- It specifies the whole table.
<TABLE BORDER = ?> - It specifies the width of border of table cells.
<TR>
- It specifies the table or row.
<TH>
- It specifies a table cell containing a heading.
<TD>
- It specifies a table cell containing data.
<BGCOLOR>
- It sets the background color of the table if specifiedwith <TABLE> tag.
<CAPTION>-
It specifies the table caption.
Creating list in HTML
Lists are used when you want to
display data in the form of points. To create a list in HTML , <LI > tag is used .This tag is an
empty tag.
HTML supports several types of lists
which are:
Ordered lists
– An ordered list is a list of items where sequence is very important. By
default, it starts with numbers. <OL> tag is used to create an ordered
list and <LI> tag is used to create different point of list.
<OL> tag supports two
attributes:
Type – It specifies the type of the
numbering to appear for an ordered list. It can be either 1,a, A or i,I.
Start – Any numeric value that gives
the starting value to a list.
Example:
<OL TYPE = “A” START = “3”>
<LI> Pencil
<LI> eraser
<LI> glue
<LI> Paper
</OL>
Unordered list
– An unordered list is a list of item where the sequence of the list is not
significant. By default it is marked with bullets. To create an unordered list
<UL> tag is used. To create each point of the unordered list <LI>
tag is used.
<UL> tag supports only one
attribute
TYPE – It specifies the type of
bullet to be displayed in a list.
<UL TYPE = “SQUARE”>
<LI> READING
<LI> PLAYING
<LI> SLEEPING
</UL>
Definition lists – A definition lists is not a single items. It is a list of
items it is a description of each item. A definition list starts with a
<DL> tag. Each term starts with a <DT> tag (definition term) followed by a definition
using <DD> tag. Thus <DT> and <DD> tags are use to create
descriptive lists.
Example:
<DL>
<DT> PALMTOP
<DD> A type of computer which
is small enough to fit in your hand.
</DL>
Nested lists
– Creating a list within another list is called a nested list. Any type of list
can be nested. For example in an ordered list an unordered list can be created.
<OL >
<LI> Pencil
<LI> eraser
<LI> glue
<LI> Paper
<UL >
<LI> READING
<LI> PLAYING
<LI> SLEEPING
</UL>
</OL>
Frames
– Frames allows to divide the web page into several independent parts, each of
these is called a frame. The frame work as an independent window allowing
multiple views at one time.
The following tags are used to
create frames in HTML:
<FRAMESET> tag
<FRAME> tag [ refer to practical 50]
Forms
– Forms are vital tools in HTML. These are used to accept information from the
user using graphical user interface (GUI ) environment. It adds interactivity
and allows communication to web documents. HTML forms are the means of
collecting information. Like forms on paper, a form on a web page allows the
user to enter the requested information and submit it for processing.
<FORM> tag is used for
creating forms in HTML [ refer to practical 52]
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