Introduction to HTML Notes & Questions | Class 7 Computer Science (IT) | Drishti OS

What you'll learn

What computer networks are and the difference between LAN, WAN, and MAN
How the internet works — IP addresses, DNS, and HTTP
The structure of an HTML page and how to use basic HTML tags
The difference between a web browser and a web server

Key concepts

1. Computer Networks

A computer network is a collection of two or more computers connected together to share data, resources (like printers), and internet access.

Types of Networks by Area:

| Type | Full name | Geographic coverage | Example | |------|----------|--------------------|---------|| | LAN | Local Area Network | A single building or campus | School computer lab, home Wi-Fi | | MAN | Metropolitan Area Network | A city or town | City-wide cable TV network, city library system | | WAN | Wide Area Network | Countries or continents | The Internet, multinational company network |

Network Topology (Physical arrangement of computers):

Topology describes how computers are connected to each other in a network.

Topology	Layout	Advantages	Disadvantages
Bus	All computers connected to a single cable	Easy to set up, cheap	If the main cable fails, the whole network fails
Star	All computers connect to a central hub/switch	Easy to add/remove computers; one failure doesn't affect others	If the central hub fails, all computers lose connection
Ring	Computers connected in a closed loop	Data flows in one direction — no collisions	If one computer fails, the whole ring can break
Mesh	Every computer connected to every other	Very reliable; multiple paths for data	Very expensive; many cables needed

Most common in schools: Star topology, because it is easy to manage and one computer's failure doesn't affect others.

2. Internet Basics

The Internet is a global WAN that connects billions of devices using a common set of communication rules (protocols).

IP Address

Every device on the internet has a unique IP (Internet Protocol) address — like a postal address for your computer.

Example IPv4 address: 192.168.1.1
Format: four numbers (0–255) separated by dots
IPv4 has about 4.3 billion possible addresses; IPv6 was developed to provide far more

DNS — Domain Name System

Computers use numbers (IP addresses), but humans prefer names. DNS translates human-readable domain names into IP addresses.

You type:  www.google.com
DNS looks up:  → 142.250.182.46
Browser connects to that IP address

Think of DNS as the phonebook of the internet — you look up a name and get a number.

HTTP and HTTPS

HTTP (HyperText Transfer Protocol) is the set of rules for transferring web pages between a browser and a server.

Protocol	Stands for	Security	Use
HTTP	HyperText Transfer Protocol	No encryption	Basic websites
HTTPS	HTTP Secure	Encrypted (SSL/TLS)	Shopping, banking, login pages

Always check for HTTPS (padlock icon in the browser address bar) before entering personal information on a website.

3. HTML Basics

HTML (HyperText Markup Language) is the standard language used to create web pages. It uses tags enclosed in angle brackets < > to mark up content.

Basic HTML Document Structure:

<!DOCTYPE html>
<html>
  <head>
    <title>My First Web Page</title>
  </head>
  <body>
    <h1>Welcome to My Website</h1>
    <p>This is my first paragraph.</p>
  </body>
</html>

Tag	Purpose
`<!DOCTYPE html>`	Tells the browser this is an HTML5 document
`<html>` ... `</html>`	Root element — wraps the entire page
`<head>` ... `</head>`	Contains page information (not visible on screen)
`<title>` ... `</title>`	Sets the browser tab title
`<body>` ... `</body>`	All visible content goes here

Headings (h1 to h6):

HTML has six levels of headings. h1 is the biggest and most important; h6 is the smallest.

<h1>This is a Main Heading</h1>
<h2>This is a Sub-heading</h2>
<h3>This is a Smaller Sub-heading</h3>

Tag	Typical use
`<h1>`	Page title — used only once per page
`<h2>`	Section titles
`<h3>`	Sub-section titles
`<h4>` to `<h6>`	Deeper nesting levels

Paragraphs:

<p>This is a paragraph of text on my web page.</p>
<p>This is another paragraph.</p>

Links (Anchor tag):

<a href="https://www.google.com">Click here to go to Google</a>

href = the URL the link points to
The text between the tags is what the user sees and clicks

Images:

<img src="photo.jpg" alt="A photo of a mountain" width="300">

src = the file path or URL of the image
alt = alternative text (shown if image can't load; important for accessibility)
width = display width in pixels

Lists:

Unordered list (bullet points):

<ul>
  <li>Apple</li>
  <li>Banana</li>
  <li>Mango</li>
</ul>

Ordered list (numbered):

<ol>
  <li>Wake up</li>
  <li>Brush teeth</li>
  <li>Eat breakfast</li>
</ol>

Tag	Meaning
`<ul>`	Unordered (bulleted) list
`<ol>`	Ordered (numbered) list
`<li>`	List item (used inside both `<ul>` and `<ol>`)

4. Web Browser vs Web Server

Feature	Web Browser	Web Server
What is it?	Software on your device to view web pages	A computer that stores and sends web pages
Examples	Chrome, Firefox, Safari, Edge	Apache, Nginx, Microsoft IIS
Role	Requests and displays web pages	Stores and delivers web pages
Who uses it?	The user (client)	The hosting company
Location	Installed on your computer/phone	Located in data centres worldwide

How it works together:

1. You type a URL in the browser
2. Browser sends a request to the web server
3. Web server finds the HTML file
4. Server sends the HTML file back to the browser
5. Browser reads the HTML and displays the page

This is called the Client-Server model — the browser is the client making requests, and the web server is the server responding.

Quick check

Your school has 30 computers all connected together in one building. What type of network is this — LAN, MAN, or WAN?
In the Star topology, what happens to the other computers if one computer breaks down? What happens if the central hub/switch breaks?
What does DNS stand for, and what is its role on the internet?
Write the correct HTML tag to create a link that says "Visit BBC" and goes to https://www.bbc.com.
What is the difference between a web browser and a web server? Give one example of each.

Open the Practice tab for graded questions on Networks and HTML.

Introduction to HTML