Internet Basics, CBSE Class 9 ICT Complete Notes

The Internet is one of the most important chapters in CBSE Class 9 ICT. Questions from this chapter appear in almost every exam. This guide covers everything you need to know about Internet basics, from the history to how it works.

What is the Internet?

The Internet is a global network of interconnected computers that communicate with each other using standardized protocols. The word "Internet" comes from Interconnected Network.

Key points to remember:

• The Internet is a network of networks
• It connects millions of computers worldwide, It uses TCP/IP protocol for communication, No single person or organization owns the Internet

Brief History of the Internet

Year	Event
1969	ARPANET was created by the US Department of Defense
1971	First email was sent by Ray Tomlinson
1983	TCP/IP protocol was adopted
1989	World Wide Web (WWW) was invented by Tim Berners-Lee
1990	First web browser was created
1991	WWW became publicly available
1995	Internet became commercially available in India through VSNL

Exam tip: The difference between the Internet and the World Wide Web is a frequently asked question. The Internet is the network infrastructure, while the WWW is a service that runs on the Internet.

How the Internet Works

The Internet works through a system of interconnected devices:

1. Client - Your computer or phone that requests information
2. Server - A powerful computer that stores and serves web pages
3. Router - Directs data packets along the network
4. ISP (Internet Service Provider) - Companies like Airtel, Jio, BSNL that provide Internet access
5. Modem - Converts digital signals to analog and vice versa

Data Transmission Process

When you type a website address in your browser:

1. Your computer sends a request to the DNS server
2. The DNS server translates the domain name into an IP address
3. The request travels through your ISP to the destination server
4. The server sends back the requested web page in data packets
5. Your browser reassembles the packets and displays the page

Important Internet Terms

IP Address

An IP Address (Internet Protocol Address) is a unique numerical label assigned to every device on the Internet. Example: 192.168.1.1

There are two versions:

• IPv4 - 32-bit address (e.g., 192.168.1.1)
• IPv6 - 128-bit address (e.g., 2001:0db8:85a3:0000:0000:8a2e:0370:7334)

Domain Name System (DNS)

DNS is like a phone book for the Internet. It converts human-readable domain names (like google.com) into IP addresses that computers understand.

URL (Uniform Resource Locator)

A URL is the complete web address of a resource. It has these parts:

https://www.example.com/page/index.html
|____| |_____________| |_______________|
Protocol   Domain Name      Path

Web Browser

A web browser is software used to access websites. Common browsers include:

• Google Chrome, Mozilla Firefox, Microsoft Edge, Safari, Opera

Web Server

A web server is a computer that hosts websites and serves web pages to clients when requested.

Internet Protocols

Protocols are rules that govern how data is transmitted over the Internet.

Protocol	Full Form	Purpose
HTTP	HyperText Transfer Protocol	Transferring web pages
HTTPS	HTTP Secure	Secure web page transfer
FTP	File Transfer Protocol	Uploading/downloading files
SMTP	Simple Mail Transfer Protocol	Sending emails
POP3	Post Office Protocol 3	Receiving emails
IMAP	Internet Message Access Protocol	Accessing emails on server
TCP/IP	Transmission Control Protocol/Internet Protocol	Base communication protocol

Types of Internet Connections

Type	Speed	Description
Dial-up	Up to 56 Kbps	Uses telephone line, very slow
Broadband	256 Kbps to 100 Mbps	High-speed, always-on connection
DSL	Up to 24 Mbps	Uses telephone line, faster than dial-up
Cable	Up to 100 Mbps	Uses cable TV lines
Fiber Optic	Up to 1 Gbps	Uses light signals, fastest
Wi-Fi	Varies	Wireless connection
Mobile (4G/5G)	Up to 1 Gbps	Uses cellular network

Internet Service Provider (ISP)

An ISP is a company that provides Internet access. In India, popular ISPs include:

• BSNL, Airtel, Jio, ACT Fibernet, Vodafone Idea

Services provided by ISPs:

• Internet connectivity, Email hosting, Web hosting, Domain registration, Technical support

Advantages of the Internet

1. Communication - Email, video calls, social media
2. Information - Access to vast amounts of knowledge
3. Education - Online courses, e-learning platforms
4. Entertainment - Streaming, gaming, social media
5. E-Commerce - Online shopping and banking
6. Job Opportunities - Remote work, freelancing

Disadvantages of the Internet

1. Security Threats - Viruses, hacking, phishing
2. Privacy Concerns - Data collection, surveillance
3. Addiction - Social media and gaming addiction
4. Cyberbullying - Online harassment
5. Misinformation - Fake news and rumors
6. Health Issues - Eye strain, sedentary lifestyle

Important Questions for Exam

Q1. What is the difference between the Internet and WWW?

The Internet is the global network of interconnected computers. The World Wide Web (WWW) is a collection of web pages and websites that can be accessed through the Internet. The Internet is the infrastructure, while the WWW is a service that uses this infrastructure.

Q2. What is the role of DNS?

DNS (Domain Name System) translates human-readable domain names like google.com into machine-readable IP addresses like 142.250.195.46. Without DNS, we would have to remember numerical IP addresses for every website.

Q3. Define protocol. Name any two Internet protocols.

A protocol is a set of rules that governs how data is transmitted over a network. Two Internet protocols are HTTP (HyperText Transfer Protocol) for transferring web pages and SMTP (Simple Mail Transfer Protocol) for sending emails.

Q4. What is an ISP? Name two ISPs in India.

An ISP (Internet Service Provider) is a company that provides Internet connectivity to users. Two ISPs in India are BSNL and Airtel.

Q5. Explain the difference between HTTP and HTTPS.

HTTP transfers data in plain text, which can be intercepted. HTTPS encrypts data using SSL/TLS certificates before transmission, making it secure. Websites with HTTPS show a padlock icon in the browser address bar.

Quick Revision Points

• Internet was started as ARPANET in 1969, WWW was invented by Tim Berners-Lee in 1989
• TCP/IP is the fundamental protocol of the Internet
• DNS converts domain names to IP addresses
• URL is the complete address of a web resource
• ISP provides Internet connectivity
• HTTP is for web pages, SMTP is for sending emails, Internet came to India in 1995 through VSNL

Understanding these basics will help you answer most Internet-related questions in your CBSE Class 9 ICT exam. Practice the important questions above and make sure you can explain each concept in your own words.