Unit 11: Internet - Subjective Questions

Internet is a global system of interconnected computer networks that use the standard Internet Protocol Suite (TCP/IP) to link billions of devices worldwide.

How it works:

• It is a network of networks consisting of private, public, academic, business, and government networks.
• Data is broken into small units called packets, which travel across routers using the TCP/IP protocol.
• Each device on the Internet has a unique IP address for identification.
• Routers and switches direct packets from source to destination, where they are reassembled.

The Internet supports a broad range of services such as the World Wide Web (WWW), e-mail, file transfer, and instant messaging.

These three terms are related but distinct:

• Web Page: A single document written in HTML that can be displayed in a web browser. It may contain text, images, videos, and links. Example: A single 'Contact Us' page.
• Website: A collection of related web pages grouped under a single domain name and hosted on a web server. Example: www.example.com containing Home, About, Products, and Contact pages.
• Homepage: The main or introductory page of a website that is displayed by default when a visitor first enters the site. It usually contains navigation links to other pages. Example: The landing page shown when you type www.example.com.

Summary:

A Web Browser is an application software used to access, retrieve, and display content available on the World Wide Web, such as web pages, images, and videos.

Main functions:

• Requesting web pages: Sends HTTP/HTTPS requests to web servers using a URL.
• Rendering content: Interprets HTML, CSS, and JavaScript to display the page.
• Navigation: Provides back, forward, refresh, and bookmark features.
• Managing history and cache: Stores visited pages for faster access.
• Security: Handles encryption (HTTPS), cookies, and warns about unsafe sites.

Examples: Google Chrome, Mozilla Firefox, Microsoft Edge, Safari, and Opera.

URL stands for Uniform Resource Locator. It is the unique address used to locate a resource (such as a web page) on the Internet.

Example: https://www.example.com:80/products/item.html

Components:

• Protocol/Scheme (https): Specifies how data is transferred (e.g., HTTP, HTTPS, FTP).
• Domain Name (www.example.com): The address of the web server hosting the resource.
• Port Number (80): Optional; identifies the specific service port on the server.
• Path (/products/item.html): The location of the specific file or resource on the server.
• Query String / Fragment: Optional parameters (e.g., ?id=5) or a section anchor (e.g., #top).

A URL ensures that a browser can uniquely identify and fetch the correct resource.

ISP stands for Internet Service Provider. It is an organization or company that provides individuals and businesses access to the Internet, along with related services.

Services provided by an ISP:

• Internet Access: Through dial-up, broadband, DSL, fiber optic, or wireless connections.
• E-mail Accounts: Providing users with email addresses and mailbox storage.
• Web Hosting: Space on servers to host websites.
• Domain Name Registration: Registering unique domain names for users.
• IP Address Allocation: Assigning static or dynamic IP addresses.
• Technical Support: Helping users configure and troubleshoot connections.

Examples: Airtel, Jio, BSNL, Comcast, and AT&T.

Hypertext is text displayed on a computer or device that contains references (hyperlinks) to other text or resources that the reader can immediately access by clicking or tapping.

Key points:

• A hyperlink is a clickable element (text or image) that connects one document to another.
• Hypertext allows non-linear navigation, meaning users can jump between related pieces of information rather than reading sequentially.
• It is written and structured using HTML (HyperText Markup Language).

Role in the WWW:

• The entire World Wide Web is built on the concept of hypertext, where web pages are linked to one another across the globe.
• HTTP (HyperText Transfer Protocol) is used to transfer these hypertext documents.
• This interlinking creates a 'web' of documents, enabling seamless movement from one page to another.

A Web Server is a computer system (hardware and software) that stores, processes, and delivers web pages to clients (browsers) over the Internet using the HTTP/HTTPS protocol.

Role and working:

• Storing content: Hosts website files such as HTML, CSS, images, and scripts.
• Receiving requests: When a user enters a URL, the browser sends an HTTP request to the server.
• Processing requests: The server locates the requested resource and may run server-side scripts.
• Sending responses: It returns the requested web page along with an HTTP status code (e.g., 200 OK, 404 Not Found).

Examples of web server software: Apache HTTP Server, Nginx, Microsoft IIS, and LiteSpeed.

The web server acts as the backbone that makes websites accessible to users worldwide.

HTML stands for HyperText Markup Language. It is the standard markup language used to create and structure content on web pages.

Main features:

• Markup-based: Uses tags (e.g., <p>, <h1>) to define elements.
• Platform independent: Works across all browsers and operating systems.
• Supports hyperlinks: Enables linking between pages using <a> tags.
• Supports multimedia: Can embed images, audio, and video.
• Easy to learn: Uses simple, readable syntax.

Basic structure:
html
<!DOCTYPE html>
<html>
<head>
<title>Page Title</title>
</head>
<body>
<h1>Main Heading</h1>
<p>This is a paragraph.</p>
</body>
</html>

• <html>: Root element.
• <head>: Contains metadata like the title.
• <body>: Contains the visible page content.

DHTML stands for Dynamic HyperText Markup Language. It is not a language itself but a combination of technologies used to create interactive and animated web pages that can change dynamically without reloading.

Technologies that combine to form DHTML:

• HTML: Provides the basic structure and content of the page.
• CSS (Cascading Style Sheets): Controls the presentation, layout, and styling of elements.
• JavaScript (Client-side scripting): Adds interactivity and dynamically changes content and styles.
• DOM (Document Object Model): Represents the page as a structured tree, allowing scripts to access and modify elements.

Advantages:

• Enables dynamic content changes (e.g., drop-down menus, animations).
• Reduces server load since changes happen on the client side.
• Improves user interaction and experience.

Example: Changing text color when a user hovers over it, without reloading the page.

XML stands for eXtensible Markup Language. It is a markup language designed to store and transport data in a structured, self-descriptive format that is both human-readable and machine-readable.

XML Example:
xml
<student>
<name>Rahul</name>
<roll>101</roll>
<course>IT</course>
</student>

Differences between XML and HTML:

Key point: HTML focuses on how data looks, while XML focuses on what data is.

Both are techniques used to make web pages dynamic, but they execute in different locations.

Client-Side Scripting:

• Executed on the user's browser (client).
• Used to enhance interactivity and validate forms.
• Languages: JavaScript, VBScript.
• Faster response as no server round-trip is needed.
• Source code is visible to the user.

Server-Side Scripting:

• Executed on the web server.
• Used to access databases, process forms, and generate dynamic content.
• Languages: PHP, ASP.NET, JSP, Python, Node.js.
• More secure as code is hidden from the user.
• Requires communication with the server.

Comparison Table:

The World Wide Web (WWW) is a system of interlinked hypertext documents and resources that are accessed via the Internet using web browsers. It was invented by Tim Berners-Lee in 1989.

Key features:

• Uses HTTP/HTTPS to transfer web pages.
• Documents are written in HTML and connected via hyperlinks.
• Each resource is identified by a unique URL.

Difference between WWW and Internet:

Key point: The Internet is the underlying infrastructure, while the WWW is one of the services that runs on it.

E-mail (Electronic Mail) is a method of exchanging digital messages between people over the Internet or a network.

Working of e-mail:

• The sender composes a message and sends it using a mail client.
• The message is transferred using SMTP (Simple Mail Transfer Protocol) to the mail server.
• The recipient's mail server stores the message.
• The recipient retrieves it using POP3 or IMAP protocols.

Components of an email address: user@example.com

• Username (user): Identifies the account holder.
• @ symbol: Separates the username from the domain.
• Domain name (example.com): Identifies the mail server/organization.

Features of e-mail:

• Attachments (files, images).
• CC (Carbon Copy) and BCC (Blind Carbon Copy).
• Fast, cheap, and asynchronous communication.

Instant Messaging (IM) is a form of real-time text-based communication between two or more people over the Internet.

Features:

• Real-time communication: Messages are delivered instantly.
• Presence indication: Shows whether a contact is online, away, or busy.
• File sharing: Allows sending images, documents, and media.
• Group chats: Multiple users can chat together.
• Multimedia support: Voice notes, emojis, video, etc.

Examples: WhatsApp, Telegram, Facebook Messenger, Slack.

Advantages over e-mail:

• Speed: Communication is instant, unlike email which may have delays.
• Interactivity: Enables continuous back-and-forth conversation.
• Presence: You can see if the other person is available.
• Informal: More suited for quick and casual communication.

Internet Telephony, also known as VoIP (Voice over Internet Protocol), is the technology that allows voice communication (phone calls) to be made over the Internet instead of traditional telephone lines.

Working:

• The analog voice signal is converted into digital data packets.
• These packets are transmitted over the Internet using the IP protocol.
• At the receiving end, the packets are reassembled and converted back into voice.

Advantages:

• Low cost: Cheaper than traditional phone calls, especially internationally.
• Additional features: Video calls, conferencing, voicemail to email.
• Portability: Can be used anywhere with Internet access.

Disadvantages:

• Dependence on Internet: Requires a stable connection.
• Power dependency: Does not work during power outages without backup.
• Quality issues: Voice quality can suffer from low bandwidth or latency.

Examples: Skype, Google Voice, WhatsApp calls, Zoom.

Video Conferencing is a technology that allows two or more people at different locations to communicate through simultaneous two-way video and audio transmission over the Internet.

Uses:

• Business meetings: Conducting remote meetings and interviews.
• Education: Online classes and distance learning.
• Healthcare: Telemedicine and remote consultations.
• Personal communication: Connecting with family and friends.

Hardware requirements:

• Camera/Webcam: To capture video.
• Microphone: To capture audio.
• Speakers/Headphones: To hear the other participants.
• Display/Monitor: To view participants.
• Fast Internet connection.

Software requirements:

• Video conferencing applications such as Zoom, Microsoft Teams, Google Meet, or Cisco Webex.

Advantages: Saves travel time and cost, enables real-time collaboration, and supports screen sharing.

The Web Browser environment consists of various components and features that help users navigate and interact with the World Wide Web.

Main components of the browser interface:

• Address Bar (URL Bar): Where the user types the website address.
• Navigation Buttons: Back, Forward, Refresh/Reload, and Stop buttons.
• Home Button: Returns to the default homepage.
• Bookmarks/Favorites: Save frequently visited sites.
• Tabs: Allow multiple pages to open in a single window.
• Status Bar: Displays loading progress and link information.
• Menu/Settings: For configuration and browser preferences.

Key features:

• History: Records visited websites.
• Cache: Stores page data for faster loading.
• Extensions/Plug-ins: Add extra functionality.
• Search Engine integration: Direct searching from the address bar.
• Security features: Pop-up blockers, private browsing, HTTPS indicators.

HTML, DHTML, and XML are all related to web development but serve different purposes.

Comparison:

Summary:

• HTML builds the basic web page.
• DHTML makes the page dynamic and interactive.
• XML is used for structured data exchange between systems.

The Internet offers a wide range of applications that have transformed modern life.

Major applications:

• World Wide Web (WWW): Accessing information through interlinked web pages.
• E-mail: Sending and receiving electronic messages instantly.
• Instant Messaging: Real-time text chatting (e.g., WhatsApp).
• Internet Telephony (VoIP): Making voice calls over the Internet (e.g., Skype).
• Video Conferencing: Face-to-face virtual meetings (e.g., Zoom).
• E-commerce: Online buying and selling of goods (e.g., Amazon).
• E-learning: Online education and courses.
• Social Networking: Connecting people globally (e.g., Facebook).
• File Transfer (FTP): Uploading and downloading files.

Transformation of communication and information sharing:

• Speed: Information travels globally within seconds.
• Accessibility: Knowledge is available to anyone, anywhere.
• Cost reduction: Cheaper communication compared to traditional methods.
• Collaboration: Enables remote work and global teamwork.
• Global reach: Breaks geographical barriers.

Overall, the Internet has made communication faster, cheaper, and more interactive than ever before.

When a user types a URL and presses Enter, several steps occur behind the scenes to display the web page:

Step-by-step process:

1. URL Entry: The user types a URL (e.g., https://www.example.com) in the browser's address bar.
2. DNS Resolution: The browser contacts a DNS (Domain Name System) server to translate the domain name into a numeric IP address.
3. Establishing Connection: The browser establishes a connection with the web server using the IP address (via TCP/IP, often over port 80 or 443).
4. HTTP Request: The browser sends an HTTP/HTTPS request to the server asking for the specific resource.
5. Server Processing: The web server processes the request, may run server-side scripts, and locates the requested files.
6. HTTP Response: The server sends back the requested page (HTML, CSS, JS, images) along with a status code (e.g., 200 OK).
7. Rendering: The browser interprets the HTML, CSS, and JavaScript and renders the page on the screen.
8. Display: The complete web page is displayed to the user.

This entire process usually happens within a few seconds.