3. The Internet
• The word "Internet" stands for International Network
• Internet is the largest computer network in the world
• Information can be sent and received through the Internet all over the world
• Internet is the network of many computer networks around the world
• It consists of millions of private, public, academic, business, and government
networks
• Communication protocol used for the Internet is TCP/IP
• Internet connects millions of computers
• These computers are linked through different communication media
• Commonly used communication media are telephone lines, fiber optic cables,
microwave, and satellite
• A large number of books, newspapers, magazines, encyclopedia, and other
types of materials are available in electronic form on the Internet
• We can find information about almost anything in the world
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4. The Internet
• We can also access the latest information or news on any topic
• It means that Internet is an ocean of knowledge
• In addition to finding information, we can communicate with other people
around world.
• Due to Internet, our world has become a global village 4
5. The Intranet
• An internal private network of an organization that can be accessed only by
the authorized users of the organization is called Intranet
• It uses Internet and Web technologies for sharing information between the
users of the same organization or company
• It looks like a private version of the Internet
• Information cannot be exchanged outside the organization
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6. The Extranet
• A network of an organization that can be accessed by authorized outside
users is called Extranet
• It is an extension of the Intranet
• It may consist of two or more intranets
• It is used for business and educational purposes
• It uses Internet technology and the public telecommunication system for
sharing business information with authorized outside users
• These users may be customers, suppliers, business partners, etc.
• An outside user accesses the Extranet by using the username and password
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7. Internet Protocols
FTP
• FTP stands for File Transfer Protocol
• This protocol exchanges files between users
• It is specially designed for uploading and downloading audio, video, graphics, and
all other different types of files
• FTP software uses this protocol for transferring files on the Internet
• Examples of FTP software are WS_FTP and Cute FTP
HTTP
• HTTP stands for HyperText Transfer Protocol
• It is a protocol used for communication between browsers and web servers (e.g.
for transferring information from web pages, stored on the web server, to the
browser)
• It was developed in 1990 when the World Wide Web (WWW) was introduced
SMTP
• SMTP stands for Simple Mail Transfer Protocol
• This protocol is used to send and receive e-mails on the Internet 7
9. Services Provided by the Internet
• Internet plays a very important role in our society
• It provides a lot of latest information about the business, education, etc.
• It has become the main medium for advertisement and communication
between users etc.
World Wide Web
• World Wide Web is commonly known as the web
• This service is used to get different information on the Internet
• World Wide Web is a vast network of HTTP servers or Web servers
• These servers store webpages (websites) that are accessible on the Internet
• World Wide Web is abbreviated as www or 3w
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10. Services Provided by the Internet
Newsgroups
• Newsgroups are discussion groups or forums
• They provide services to exchange messages on Internet about a particular subject
• This facility is provided on the Internet on special servers known as News servers
Chatting
• Internet provides facility to chat (talk) with people online all over the world
• Different programs like MSN Messenger, Yahoo Messenger, AOL online, etc. are
available for chatting on the Internet
• Chat rooms allow users to participate in a chat on the Internet
E-mail
• E-mail stands for electronic mail
• It is the most popular service provided by the Internet
• It provides a fast and efficient way to send and receive messages through the
Internet. You can send different types of files can also be sent through e-mail
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11. Services Provided by the Internet
E-Commerce
• E-Commerce stands for Electronic Commerce
• It is a very important service provided by the Internet through which
financial transactions are carried out over the Internet
• It is the modern way to run a business on an international basis
• When business is conducted with the help of computer networks, this
activity is usually termed as e-commerce or e-trade
• Examples of E-commerce are: online shopping, online advertising, online
banking, etc.
• Through e-commerce, goods can be purchased and sold from anywhere in
the world
• Credit cards are used for payments
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12. Terminologies & Tools used for
Internet
Chapter 8 – The Internet & Computer Security
12
13. Terminologies & Tools used for Internet
Web Server
• A computer on the network (i.e. Internet) in which websites or web pages
are stored is known as a web server
• We access a web page or website from a web server through a web browser
• We send a request to the web server through a web browser
• Web server receives the request and sends back information of the web
page or website through the web browser
• Nowadays millions of web servers are providing these services on the
Internet
Client
• Hardware and software through which user gets information from server as
well as sends information to other users through server is called client
• Usually, personal computers and browser programs are used to get
information from server
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14. Terminologies & Tools used for Internet
Web Browser
• A software that is used to access websites or web pages is known as a web
browser
• A user enters the URL of the website in the address bar of the browser window
• Browser accesses the website or web page and its information are displayed in the
main window of the browser
• Many web browsers are available
• Examples → Internet Explorer, Google Chrome, Opera, Mozilla Firefox, and Safari
Web Page
• A document on the Web (World Wide Web) is called a web page
• This document can contain text, graphics, audios, videos, and links to other web
pages
Website
• A collection of related web pages is called a website
• A website may contain many web pages and some other files
• A user can access any website through a web browser
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15. Terminologies & Tools used for Internet
Home Page
• Main page or title page of the website is known as the home page
• It provides an introduction to the website
• This page is downloaded first when the website is accessed
• Usually, all links of other pages of the website are given on the home page
• Therefore, other pages of the website are visited or accessed through the
home page
Web Hosting
• Web hosting is the service which provides the online storage space for
storing website or web pages on the web servers
• Companies which provide storage space on their web servers are known as
web hosts
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16. Terminologies & Tools used for Internet
HTML
• HTML stands for Hyper Text Markup Language
• HTML is a computer language
• It is used to create web pages/websites
• This language provides commands (or keywords) for creating HTML documents
• These commands or keywords are called tags
• These tags are used for defining the layout (or structure) of a web page, formatting
text of a web page, and linking other web pages
URL Address
• URL stands for Uniform Resource Locator
• It is an address of a web page or website on the Internet
• Every web page has a unique address
• A web page can only be accessed if we know the URL of that page
• For example, Google is the most popular website and its URL is
http://www.google.com 16
18. Advantages of the Internet
+ Sharing Information
+ Collection of Information
+ News
+ Searching Jobs
+ Advertisement
+ Communication
+ Entertainment
+ Online Education
+ Online Results
+ Online Airlines and Railway Schedules
+ Online Medical Advice
• Details are given in book “Introduction to Computer” – PM Series 18
19. Disadvantages of the Internet
- Viruses
- Security Problems
- Immorality
- Filtration of Information
- Accuracy of Information
- Wastage of Time
• Details are given in book “Introduction to Computer” – PM Series
19
21. Search Engines
• A search engine is a special website on the Internet
• It is used to search different information on the Internet (or web)
• A lot of information is available on the Internet on different websites or webpages
• There are billions of websites on the Internet
• We cannot remember the URLs of all the websites
• We can search different websites or webpages and information stored in them
through search engines
• Search engines maintain a list of billions of webpages containing information on
various topics
• Many search engines are available on the Internet
• YAHOO http://www.yahoo.com
• ALTA VISTA http://www.altavista.com
• ASK http://www.ask.com
• GOOGLE http://www.google.com
• EXCITE http://www.excite.com
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22. Search Engines
Searching Information using Search Engine
• Some keywords (i.e. words) related to the topic or information being
searched are given to search engine
• Search engine searches the required information and sends the addresses of
webpages containing the required information to the user’s computer
• For example, to search information about the "History of the Internet", give
these words to any search engine
• Search engine will search the given information and will provide a list of links
of webpages or websites along with a brief description of each webpage
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24. Computer Security
• Today, critical or important information of many organizations is stored and
managed on computers and mobile devices
• Information may be credit card numbers, customer’s bank account
information, and purchase information
• Computers and mobile devices, along with the information they store, are
accessible and available when needed
• Many organizations provide online services to their customers/users
• Data is stored online for providing fast services
• For example
• A credit card company may put data of its customers online
• A bank providing online services
• A university may provide the facility of viewing results online. Similarly, people take
online exams like GRE, GUAT, etc.
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25. Computer Security
• Data/information can be lost or destroyed or misuse due to different reasons
• It can be deleted or destroyed accidentally or intentionally
• Data is more valuable than computer hardware and software
• In case of failure of hardware, it can be replaced
• Similarly, in case of loss of software, it can be re-installed
• But in case of data loss, it is difficult to recover in time
• Organizations must take measures (or necessary arrangements) to protect or
safeguard their computers, mobile devices, and information/data they store,
from loss, damage, and misuse.
• Protecting a computer system and its resources (such as hardware, software,
and information or data) from being damaged or accessed by unauthorized
persons is called computer security
• Different methods are used to ensure the security of a computer system 25
26. Authorized Access & Unauthorized Access
• Accessing a computer or its resources legally is called authorized access
• Sometimes a legal user is restricted to a specific level of access
• This level of access of a user is known as his/her authorized access
• A process to check the rights of a user to access a particular computer
system is called authorization
• Accessing a computer or its resources illegally is called unauthorized access
• When someone tries to exceed his/her level of access, it is considered
unauthorized access
• Unauthorized access to a computer or its resources is a crime
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28. Computer Virus
• A program or piece of code that infects or affects the computer system or mobile device
and files/programs stored in it is called a virus
• It can load into the user’s computer primary or secondary memory without his/her
knowledge
• The code for a computer virus is written in a programming language
• This code is attached to a file such as a program file
• A file containing a virus is called an infected file
• When the infected file is copied to a disk, the virus is also copied and it hides itself or
attaches to other files on the disk
• A disk that contains virus/viruses is called an infected disk
• Different computer viruses create different problems in different ways
• A virus may destroy all data stored in the hard disk by formatting it
• A virus may change the boot sector of the hard disk. If the boot sector of a disk is affected, it cannot boot the
computer
• A computer virus is automatically loaded from disk into the memory of the computer. It slows down the data
accessing speed of the computer
• A virus may detect some special information like passwords or any sensitive data and send it to some other user on
a network. For example, a virus may read the ‘Pin Code’ of a credit card, entered by a user, and then sends this
information to another user. 28
29. Activation of a Virus
• When a virus performs its actions, it is called the activation of a virus
• Different computer viruses are activated in different ways
• For example, some viruses are activated on a fixed date
• Usually, these viruses are part of the application programs (or operating
systems)
• When the application program is run on the computer, it checks the system
date
• If the system date matches with the activation date of the virus, the virus is
activated
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30. Causing of Spreading Viruses
Removable Storage Media
• In a flash drive / CDs, some files may be infected by viruses
• When a user copies infected files from a flash drive into his/her computer, viruses are also
transferred/copied
Networks
• In a computer network, if a computer is infected by a virus then this computer may infect other computers
in the network also
• For example, when users access the infected computer in the network, viruses are transferred or copied
into their computers with downloaded files.
Insecure Websites
• There are many websites on the Internet that are not completely secure
• When we access these insecure websites then viruses are also automatically downloaded and infect our
computers
Email Attachment
• An email may contain an infected file attachment
• When a user opens an infected email attachment, virus may infect computer
• This virus is also transferred to other computers when email messages are sent from the infected computer
to them
Pirated Software
• Word ‘pirated’ means ‘copied illegally’
• Software which is installed and used illegally (or without a license) is called pirated software
• Pirated software is also a major source of spreading viruses 30
32. Antivirus Programs
• A software that detects and removes viruses from the computer or mobile device
is known as an antivirus program
• Most antivirus programs can also detect and remove viruses from the computer or
mobile device
• Many antivirus programs automatically scan all types of removable storage devices
inserted in the computer or mobile device, files downloaded from the web, and
email attachments
• These programs also prevent viruses from entering into the computer
• Most of the email servers and web servers also have antivirus programs installed
to check incoming and outgoing email messages and files for viruses
• A large number of antivirus programs are available
• These programs contain a list of known viruses
• They also contain methods for removing these viruses from infected files or disks
• However, there is no single antivirus software, which can remove all types of
viruses
• If an antivirus identifies/detects an infected file, it attempts to remove the viruses
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33. Antivirus Programs
• Latest antivirus software must be installed on the computer to save the
computer from new viruses
• We should update antivirus and scan the computer system regularly
• Examples of Antivirus
• Symantec
• McAfee
• AVG
• Avast
• Kaspersky
• NOD 32
• Windows defender
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34. Some Important long Questions
1. What is the Internet? How we access it.
2. Distinguish between the Internet, Intranet and Extranet.
3. What services are provided by the Internet?
4. What is Search Engine? How it helps us?
5. What is Computer Security? Distinguish between Authorized and
Unauthorized access.
6. What is Computer virus? How it gets activated and spread?
7. What is Antivirus program? List few examples.
8. What is eCommerce? How can we utilize it for our benefit.
*note: Please don’t limit yourselves to these long questions only, examiner
can ask you about same material in different context.
You can extract several short questions as subset of these long questions.
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35. For more details, refers to
PM Series
Introduction to Computer
by
CM Aslam, Aqsa Aslam, Mussadiq Fida, & Mudassir
Ahmad
Publisher:Majeed Sons
22- Urdu Bazar, Lahore
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