Internet, IoT, HTML, WWW & Browsers
📑 सामग्री सूची
What is the Internet?
The Internet is a worldwide network of interconnected computers that communicate using the TCP/IP protocol suite. It allows users to share information, send emails, browse websites, watch videos, use cloud services, and conduct online transactions.
Features of Internet: Global connectivity · Fast communication · Information sharing · Remote access · Online education · Cloud computing · E-commerce
Internet vs World Wide Web (WWW)
| Internet | WWW |
|---|---|
| Physical network of computers | Collection of web pages |
| Uses TCP/IP | Uses HTTP/HTTPS |
| Developed before WWW | Introduced in 1989 |
| Provides many services | One service of Internet |
Exam Point: Internet ≠ WWW — The WWW is a service running on the Internet.
What is WWW?
WWW (World Wide Web) is a system of interlinked web pages connected using hyperlinks. It allows users to access information through browsers.
Inventor: Sir Tim Berners-Lee · Introduced: 1989
Components of WWW
- Web Browser
- Web Server
- HTML
- URL
- HTTP/HTTPS
What is HTML?
HTML stands for HyperText Markup Language. It is the standard language used to create web pages and describes the structure of a webpage using tags.
Features of HTML: Easy to learn · Platform independent · Uses tags · Supports multimedia · Supports hyperlinks · Compatible with all browsers
Basic Structure of HTML
<!-- HTML5 Document -->
<!DOCTYPE html>
<html>
<head>
<title>My First Web Page</title>
</head>
<body>
<h1>Welcome</h1>
<p>This is HTML.</p>
</body>
</html>
Important HTML Tags
| Tag | Purpose |
|---|---|
<html> | Root element |
<head> | Metadata |
<title> | Page title |
<body> | Visible content |
<h1> to <h6> | Headings |
<p> | Paragraph |
<a> | Hyperlink |
<img> | Image |
<table> | Table |
<form> | Form |
<input> | Input field |
<button> | Button |
<ul> | Unordered list |
<ol> | Ordered list |
<li> | List item |
<iframe> | Inline frame (HTML5) |
<audio> | Audio (HTML5) |
<video> | Video (HTML5) |
Hyperlink
<a href="https://example.com">Visit</a>
The href attribute specifies the destination URL.
HTML Versions
| Version | Year |
|---|---|
| HTML 1.0 | 1993 |
| HTML 2.0 | 1995 |
| HTML 3.2 | 1997 |
| HTML 4.01 | 1999 |
| XHTML | 2000 |
| HTML5 | 2014 (Current Standard) |
Exam Point: HTML is a markup language, not a programming language. HTML5 is the latest standard.
Web Browsers
A Web Browser is software that retrieves and displays web pages from web servers. Examples include Google Chrome, Mozilla Firefox, Microsoft Edge, Safari, Opera, and Brave.
Functions of Browser
- Opens websites
- Downloads files
- Executes JavaScript
- Renders HTML and CSS
- Stores cookies
- Saves browsing history
Browser Components
- Address Bar
- Back/Forward Buttons
- Refresh Button
- Tabs
- Bookmarks
- Download Manager
Popular Browsers
| Browser | Company |
|---|---|
| Chrome | |
| Edge | Microsoft |
| Firefox | Mozilla |
| Safari | Apple |
| Opera | Opera Software |
What is IoT?
IoT stands for Internet of Things. It connects physical devices to the Internet for communication and automation.
Examples: Smart TV · Smart Watch · Smart Bulb · Smart Car · Smart Home · Fitness Band
Components of IoT
- Sensors
- Internet Connectivity
- Cloud
- Data Processing
- User Interface
IoT Protocols
| Protocol | Transport | Use Case |
|---|---|---|
| MQTT | TCP (Port 1883) | Lightweight publish-subscribe for constrained devices |
| CoAP | UDP | RESTful communication for IoT |
| HTTP | TCP (Port 80) | Standard web communication (overhead-heavy) |
| HTTPS | TCP (Port 443) | Secure web communication |
Exam Point: MQTT (Message Queuing Telemetry Transport) is a lightweight protocol commonly used over TCP/IP for constrained resource nodes in IoT architectures.
Advantages of IoT
- Automation
- Remote monitoring
- Energy efficiency
- Smart healthcare
- Smart agriculture
- Smart cities
HTTP, HTTPS & URL
| Concept | Full Form | Default Port | Key Feature |
|---|---|---|---|
| HTTP | HyperText Transfer Protocol | 80 | Stateless protocol for web transfers |
| HTTPS | HTTP Secure | 443 | HTTP over TLS/SSL encryption |
| DNS | Domain Name System | 53 (UDP) | Translates domain names to IP addresses |
| URL | Uniform Resource Locator | — | https://www.example.com/about.html |
Memory Trick: "80 HTTP, 443 HTTPS" — 80 is "H"appy, 443 is "S"ecure.
Previous Year Questions (PYQs)
Q1. Which tag in HTML is used to define an inline frame for embedding another document?
Answer: <iframe> Rajasthan Instructor
The
<iframe> tag specifies an inline frame embedded within the current HTML document.Q2. What is the main structural difference between HTML and XML?
Answer: HTML tags are predefined, XML tags are custom-defined and case-sensitive Rajasthan Instructor
HTML focuses on presenting data using predefined tags. XML focuses on storing/transporting data with custom-defined, case-sensitive tags.
Q3. In IoT architectures, which protocol is lightweight and commonly used over TCP/IP for constrained resource nodes?
Answer: MQTT Rajasthan Instructor
MQTT is a lightweight publish-subscribe messaging protocol ideal for low-bandwidth, high-latency IoT sensor networks.
Q4. [GATE] Identify the correct chronological order of packets leaving a host when requesting a webpage in a fresh browser session (empty cache)
Answer: DNS → TCP SYN → GET Index → GET Image GATE CSE
DNS Lookup → TCP Handshake → HTTP GET for base HTML → HTTP GET for embedded resources.
Q5. [GATE] A graphical HTML browser accesses a static HTML page containing exactly ONE embedded image. Assuming non-persistent HTTP without caching
Answer: At least 2 HTTP requests, each in a separate TCP connection GATE CSE
Under non-persistent HTTP, each object request requires a separate TCP connection.
Q6. In HTML5, which tag is used to embed audio files natively without third-party plugins?
Answer: <audio> DSSSB/KVS
HTML5 introduced native media tags including
<audio> and <video>.Q7. Which HTTP response status code represents "301"?
Answer: 301 Moved Permanently DSSSB/KVS
200: Success · 301: Permanent URL redirection · 404: Resource missing · 500: Server error.
GATE / DSSSB / KVS Important One-Liners
• HTML stands for HyperText Markup Language
• WWW was invented by Tim Berners-Lee in 1989
• HTTP uses Port 80
• HTTPS uses Port 443
• HTML is a markup language, not a programming language
• Chrome is developed by Google
• Firefox is developed by Mozilla
• Edge is developed by Microsoft
• IoT means Internet of Things
• HTML5 is the latest HTML standard (2014)
• <iframe> is used for inline frames in HTML5
• <audio> and <video> are HTML5 media tags
• MQTT is a lightweight IoT protocol over TCP (Port 1883)
• DNS uses UDP Port 53
• HTTP status 301 = Moved Permanently
Quick Revision Cards
5 Min
Internet & WWW
- Internet — Physical network of computers
- WWW — Collection of web pages (1989, Tim Berners-Lee)
- HTTP — Port 80 (unencrypted)
- HTTPS — Port 443 (encrypted)
- DNS — Port 53 (UDP) — Domain → IP
- URL — Uniform Resource Locator
5 Min
HTML Basics
- HTML — HyperText Markup Language
- HTML5 — Latest standard (2014)
- <html> — Root element
- <head> — Metadata
- <body> — Visible content
- <a href=""> — Hyperlink
- <iframe> — Inline frame
- <audio> / <video> — HTML5 media
5 Min
Browsers & IoT
- Chrome — Google
- Firefox — Mozilla
- Edge — Microsoft
- Safari — Apple
- IoT — Internet of Things
- MQTT — Lightweight IoT protocol (TCP, Port 1883)
- CoAP — UDP-based IoT protocol
Memory Trick: "HTML → HyperText Markup Language" · "HTTP 80, HTTPS 443" · "MQTT = Message Queuing"
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Quick Revision Checklist
- ✅ HTML: HyperText Markup Language (Markup, not programming)
- ✅ WWW: Invented by Tim Berners-Lee in 1989
- ✅ HTTP Port: 80 · HTTPS Port: 443
- ✅ DNS: Port 53 (UDP) — Domain → IP
- ✅ HTML5: Latest standard (2014) with
<audio>,<video>,<iframe> - ✅ Browsers: Chrome (Google), Firefox (Mozilla), Edge (Microsoft)
- ✅ IoT: Internet of Things — MQTT (TCP, Port 1883) is lightweight
- ✅ Internet ≠ WWW: WWW is a service on the Internet
Master these concepts to score high marks in GATE, DSSSB, KVS & other CS exams. Good luck!