Syllabus
Syllabus
Internet: World Wide Web, web servers, web clients, web sites, web pages, web browsers, blogs, news groups, HTML, web address, e-mail address, downloading and uploading files from a remote site.
Internet protocols: TCP/IP, SMTP, POP3, HTTP, HTTPS.
Remote login and file transfer protocols: SSH, SFTP, FTP, SCP, TELNET, SMTP, TCP/IP.
Services available on the internet: information retrieval, locating sites using search engines and finding people on the net.
Web services: chat, ernail, video conferencing, e-Learning, e-Banking, eShopping, e-Reservation, e-Govemance, e-Groups, social networking.
Mobile technologies: SMS, MMS, 3G, 4G, 5G
Internet
1. The Internet’s Origins: ARPANET (1960s-1970s)
- The Origins of the Internet: ARPANET (1960s-1970s)
- The foundation of the modern internet was laid with the development of ARPANET, a pioneering project that revolutionized digital communication.
1. The Catalyst: The Cold War Context
- Agency: The project was initiated by the Advanced Research Projects Agency (ARPA), a branch of the U.S. Department of Defense. ARPA (now known as DARPA) was created in response to the Soviet Union’s launch of the Sputnik satellite, with the mission to ensure the U.S. maintained a technological lead.
- Primary Goal: The primary military-driven goal was to create a decentralized communications network. In a traditional centralized network, a single destroyed hub (like a command center) could cripple the entire system. ARPA wanted a network that could withstand the loss of multiple nodes and still allow remaining parts to communicate.
2. The Revolutionary Technology: Packet Switching
- The Problem: The existing telephone system used circuit switching, which established a dedicated physical path for the entire duration of a call. This was inefficient and vulnerable for data transmission.
- The Solution: Packet switching, a concept developed by pioneers like Paul Baran, Donald Davies, and Leonard Kleinrock.
- Data (a message, a file) is broken down into smaller, standardized blocks called packets.
- Each packet is sent independently across the network, taking the most efficient route available at that millisecond.
- Packets are reassembled into the original data at the destination.
- Why it was Key: This method ensured the network had no single point of failure. If one route was destroyed, packets would simply be re-routed along another path. It also allowed for much more efficient use of network lines.
3. Key Milestones and Demonstrations
- The First Message (1969): On October 29, 1969, the first ARPANET link was established between a computer at UCLA and another at the Stanford Research Institute (SRI). The first attempted message was the command “LOGIN”. The system crashed after transmitting just the first two letters: “LO“. Despite the crash, it was a historic success. An hour later, a full connection was established.
- The First Network: By the end of 1969, four nodes (UCLA, SRI, UC Santa Barbara, and the University of Utah) were connected, forming the first wide-area packet-switched network.
- The “Killer App”: Email (1971): While file transfer and remote computer access were the initial goals, a new application quickly became the network’s most popular feature. In 1971, programmer Ray Tomlinson created the first email program. He also chose the @ symbol to separate the user’s name from their machine name. Email demonstrated the network’s profound potential for person-to-person communication, a use its creators had not fully anticipated.
4. Lasting Legacy
- ARPANET was decommissioned in 1990, but its principles became the bedrock of the global internet.
- It proved the practical viability of packet-switched networking.
- It developed the core communication protocols (like TCP/IP, which was adopted in 1983) that the internet still runs on today.
- It created a community of researchers and users who fostered the culture of open collaboration and innovation that defines the internet.
- In essence, ARPANET was the crucial first experiment that transformed a theoretical concept—a resilient, decentralized network—into a working reality that would eventually connect the world.
2. The Birth of the “Internet” (1980s)
- To connect different computer networks together, two scientists, Vinton Cerf and Bob Kahn, created TCP/IP (Transmission Control Protocol/Internet Protocol).
- This set of rules became the standard language for all networks to communicate.
- On January 1, 1983, all computers on ARPANET officially switched to TCP/IP. This is considered the birth of the modern internet.
- The NSFNET, funded by the National Science Foundation, expanded the network to universities and research centers, eventually allowing commercial use.
3. The World Wide Web’s Invention (1989-1993)
- Tim Berners-Lee, a British scientist at CERN, wanted to create a system for scientists to easily share information.
- He proposed a “universal linked information system” based on hypertext—text that links to other documents.
- To make this system, he created three key things:
- HTML: The language for making web pages.
- HTTP: The protocol for transferring web pages.
- URL: The unique address for each web page.
- He created the first web browser and server in 1990.
- In 1993, CERN made the web’s code publicly available for free, which allowed anyone to use it without paying fees. This was the single most important event that led to the web’s massive growth.
4. The Web Goes Mainstream (1993-2000s)
- The Mosaic web browser, released in 1993, was the first to have a graphical, “point-and-click” interface. This made the web easy for everyone to use, not just scientists.
- The web’s popularity led to the dot-com boom, a period of rapid growth and investment in internet companies.
- Early search engines like Yahoo! and AltaVista helped people find information on the growing number of websites.
5. The Modern Web (2000s-Today)
- The early 2000s brought Web 2.0, a new phase where the web became interactive and social.
- Platforms like MySpace, Facebook, and YouTube allowed users to create and share their own content.
- The launch of the iPhone in 2007 made the web mobile and always available.
- Today, the web is a complex ecosystem that is integrated into almost every part of our lives, from communication to commerce and entertainment.
World Wide Web and Subtypes
The World Wide Web (WWW) is the collection of publicly accessible interlinked web pages on the Internet. It includes a variety of website types:
- Blog: Personal journal sites (e.g., medium.com, blogger.com).siyavula
- Weblog: Online log of events, somewhat similar to a blog (e.g., tech blogs tracking changes in software).siyavula
- Social Network: Platforms for user interactions (e.g., facebook.com, instagram.com, linkedin.com).siyavula
- Wiki: Collaborative sites where users edit content (e.g., wikipedia.org, wikitravel.org).siyavula
- Web Application: Interactive tools and utilities (e.g., budget calculators, Google Docs, online banking portals).geeksforgeeks+1
- E-commerce: Online shops (e.g., amazon.in, flipkart.com).
- News Website: Dedicated to current events (e.g., bbc.com, ndtv.com).
- Educational Portal: Resource sites (e.g., khanacademy.org, coursera.org).oncrashreboot
- Messaging Board/Forum: Discussion platforms (e.g., stackoverflow.com, reddit.com).wikipedia+1
Web Servers and Their Types
A web server is where website data is stored and served. Examples and subtypes:
- Static Server: Delivers fixed HTML pages (e.g., informational company sites).wikipedia
- Dynamic Server: Creates content based on user input (e.g., Facebook, online banking).w3
- Cloud Server: Websites hosted on distributed infrastructure (e.g., Google Cloud, AWS).wikipedia
Examples: Apache, Nginx, Microsoft IIS, Google’s own web servers.
Web Clients and Their Types
Web clients are software or devices that access web servers. Examples and subtypes:
- Browser Client: Chrome, Firefox, Edge, Safari.ou
- Mobile Clients: Apps (e.g., Instagram mobile app accessing APIs).
- Command-line Clients: curl, wget for developer use.
- Embedded Clients: Smart TVs and IoT devices accessing websites.
Websites and Subtypes
A website is a collection of related pages under one domain. Subtypes:
- Personal Website: Individual portfolios or information (e.g., artist homepages).wikipedia
- Corporate/Business Website: For companies (e.g., tcs.com).
- Government Website: e.g., india.gov.in.
- E-commerce Website: Shopping platforms (e.g., amazon.in).
- Entertainment Website: Streaming media (e.g., netflix.com).oncrashreboot
- Educational Website: Learning resources (e.g., coursera.org).oncrashreboot
- Subscription Site: Paid access (e.g., academic journals, gaming sites).wikipedia
Web Pages and Types
A web page is an individual document, usually built with HTML. Types include:
- Home Page: Main entry point.
- Landing Page: Designed for marketing or offers.
- Contact Page: Provides ways to reach owners.
- Product Page: Describes or sells a product.
- Article/Page: Informative content.
Web Browsers and Examples
Web browsers help access and render web content:
- Google Chrome, Mozilla Firefox, Safari, Microsoft Edge, Opera Mini.
Browsers support features like tabbed browsing, bookmarks, private browsing, and extensions.siyavula
Blogs and Their Types
Blog: Written journals online. Types:
- Personal Blog: Life stories, travel diaries.
- Professional Blog: Career advice, industry news.
- Niche Blog: Focused on hobbies or interests (e.g., food blog, tech blog).
News Groups/Subtypes
News group: Online discussion forum. Subtypes:
- Topic-specific: sci.math, rec.music.
- General: alt.news, soc.culture.
HTML and Subtypes
HTML is a markup language for web pages. Subtypes:
- HTML 4: Classic format.
- HTML5: Modern, supports video, audio, graphics.
Examples:
xml<h1>Heading</h1>
<a href="https://www.example.com">Link</a>
<input type="text">
Web and E-mail Address
- Web Address (URL): https://www.google.com, https://en.wikipedia.org.wikipedia
- E-mail Address: alice@gmail.com, info@abcd.com.