Basics of Computer System Class 9 Notes

Basics of Computer System Class 9 Notes – Communication is the process in which a person can share their ideas, thoughts, and feelings with other people. Computer and communication technologies have transformed the way we exchange information.

Basics of Computer System Class 9 Notes

History of the Internet

In 1957, the US government set up a special agency called the Advanced Research Projects Agency (ARPA) under the Department of Defense.

The first network called the Advanced Research Projects Agency Network (ARPANET) became operational in 1969. It initially consisted of universities and research laboratories for information sharing.

Data Transmission over the Internet

For transmission of data, the internet uses the packet-switching technology. The packet switching broke larger messages into smaller pieces, known as packets. Each packet is labelled with the sequence number, destination address, and other relevant information. The packets then travel independently over the network to the destination.

World Wide Web (WWW)

The World Wide Web (WWW), is a large collection of online documents like text, pictures, audio and video clips, and animations. WWW uses the HTTP for the transfer of these documents over the internet.

Web browser

The name browser  comes from the word ‘browse’, which means to navigate, browser is an application program used to look at and interact with all the information on the WWW.

Web pages

A web page is a document on the WWW created using hypertext markup language (HTML). It may contain different types of data like text, hyperlinks, images, videos, tables, and so on.


A website is a group of linked web pages on the World Wide Web that are given a special name. The unique name of the website is called its domain name. The First page of the website is called its home page.

Web servers

A web server  is a program on a server computer that hosts a large number of web pages and delivers the requested web pages to the clients.

Doman name or Web address

The special name that identifies a website on the internet is called a domain name.  For example,, and are the domain names of some popular websites. A domain name has two or more parts—Name and Extension. For example, in the domain, ‘cbseskilleducation’ is the name and ‘.com’ is the extension.

IP Address

Every computer in a network should have a unique identity number. This unique identity of each computer on a network is known as an IP address. An IP address is a 32-bit address represented in four groups of numbers from 0 to 255. These groups are separated by periods. For example, could be an IP address.

Domain Name System

The domain name system (DNS) is a system that converts the domain names of web resources into IPaddresses on the internet or on local networks that use the TCP/IP protocol.

Uniform Resource Locator

A Uniform Resource Locator  (URL) is the address or location of a resource (for example, a web page) on the WWW.


A blog is a website that allows users to share opinions and discuss various topics in the form of an online journal. A blog is generally based on a particular topic or theme.

Features of a blog

  • A blog is normally a single page of entries.
  • A blog is a collection of recent information.
  • A blog is normally public—the whole world can see it.
  • A blog’s entries are often written by just one author.


Newsgroup is like an electronic bulletin board which allows people to communicate with people who share common interests. For example, if someone wants to discuss or learn about the latest developments in IT, he or she can join an IT group. Such a group on the internet where one can share ideas on a specific topic with other people is called a newsgroup.


A set of such rules and conventions that specify how the data will be transferred between the computers on a network is called a protocol.

  • Transmission control protocol/internet protocol (TCP/IP) – TCP/IP is the combination of two protocols transmission control protocol (TCP) and internet protocol (IP). Data is sent between computers connected to a network via TCP/IP.
  • Simple mail transfer protocol – It is used for sending electronic mail over the computer network.
  • POP3 – POP3 stands for post office protocol. It is a standard protocol used to receive emails from a server.
  • Hypertext transfer protocol – The hypertext transfer protocol (HTTP) allows the transfer of hypertext documents on the World Wide Web (WWW).
  • Hypertext transfer protocol secure (HTTPS) – HTTPS use SSL and TLS to transfer the data over the computer network. This prevents hackers from reading and modifying the sensitive data.

Remote Login Protocols

The term “remote login” describes getting authorized user access to a computer or network from a distance. We can access a computer without being present physically. There are two most commonly used remote login protocols.

  • Secure shell (SSH) – SSH protocol allows a user to login from a remote computer and provides secure communication over a network. It ensures that the communication between the two remote computers occurs in the encrypted manner so that the communication and data transfer is safe.
  • Telnet – TELNET stands for TELetype network. It is a network protocol that allows a user to log into a remote host and execute commands on it as if they were logged in locally.

File Transfer Protocols

The file transfer protocol (FTP) is a protocol used to transfer files between computers on a network. Using FTP, files can be uploaded to or downloaded from an FTP server to a local computer.

  • SFTP – It is a secure way of transferring a file, It allows FTP to first use the secure shell protocol to establish a secure connection and then the file gets transferred over the network. The file is delivered in an encrypted version, which ensures its safety and security.
  • SCP – It stands for secure copy protocol. It is basically a file transfer protocol that is used to transfer files between the host and the server over a computer network. It also uses the secure shell protocol to get the secure connection for file transfer and works like SFTP

Basics of Computer System Class 9 Notes

Basics of Computer System Class 9 Notes

Basics of Computer System Class 9 Notes

Basics of Computer System Class 9 Notes

Basics of Computer System Class 9 Notes

Basics of Computer System Class 9 Notes

Basics of Computer System Class 9 Notes

Basics of Computer System Class 9 Notes

Basics of Computer System Class 9 Notes

Basics of Computer System Class 9 Notes

Basics of Computer System Class 9 Notes

Basics of Computer System Class 9 Notes

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