Unit 7: Internet and Internet Applications

Introduction

The Internet is a global network of networks that connects billions of devices using the TCP/IP protocol suite. It allows people, businesses, and governments to exchange information, conduct business, and access services across the world.

History of the internet

• 1969 — ARPANET, the first packet-switched network, was launched by the US Department of Defence.
• 1972 — first email program.
• 1983 — TCP/IP became the standard protocol for ARPANET.
• 1989 — Tim Berners-Lee invented the World Wide Web at CERN.
• 1991 — the first website went live.
• 1990s — commercial internet, dot-com boom.
• 2000s — broadband, Wi-Fi, mobile internet, Web 2.0.
• 2010s onwards — smartphones, cloud, social media, streaming.
• 2020s — AI, IoT, 5G, blockchain, Web3.

Managing the internet

No single organisation owns the internet, but several bodies coordinate it:

• ICANN — manages domain names and IP addresses.
• IETF — develops internet standards (RFCs).
• W3C — develops web standards (HTML, CSS).
• ISOC — promotes internet development.
• Regional Internet Registries (RIRs) — allocate IPs in regions (APNIC for Asia).

Connecting to the internet

To connect, you need:

1. An ISP (Internet Service Provider) like Worldlink, Vianet, Comcast, Jio.
2. A modem / router to connect to the ISP.
3. A device (PC, phone, etc.).
4. A medium (cable, fiber, Wi-Fi, mobile data, satellite).

Internet connections

Common connection types:

• Dial-up — old, slow, uses phone line (kbps).
• DSL — over phone lines, faster than dial-up.
• Cable — over TV cable.
• Fiber-to-the-home (FTTH) — gigabit speeds.
• Wireless / Wi-Fi — within homes and offices.
• Mobile (4G / 5G) — internet via phone networks.
• Satellite — for remote areas (Starlink, VSAT).

IP address and Domain Name System (DNS)

IP address

Every device on the internet has a unique IP address:

• IPv4 — 32-bit, e.g. 192.168.1.1.
• IPv6 — 128-bit, e.g. 2001:db8::1.

DNS

The Domain Name System translates human-readable names like google.com into IP addresses. It works like a phonebook for the internet.

Components:

• Root servers — top of the DNS hierarchy.
• TLD servers — .com, .org, .np.
• Authoritative servers — hold the actual records.
• Recursive resolvers — what your ISP runs (e.g. 8.8.8.8).

Client-server architecture

Most internet services use the client-server model:

• Client — your browser, phone app, or computer making the request.
• Server — a remote computer that responds with the requested data.

Example: when you open YouTube, your phone (client) requests a video from YouTube’s servers, which stream it back.

Modern variations:

• Peer-to-peer (P2P) — every node is both client and server (BitTorrent).
• Cloud / distributed — services run across many servers worldwide (Netflix on AWS).

Hypertext Transfer Protocol (HTTP)

HTTP is the protocol used for transferring web pages.

• Uses port 80 (HTTP) or 443 (HTTPS, secure).
• Request methods: GET, POST, PUT, DELETE.
• Status codes: 200 OK, 301 Moved, 404 Not Found, 500 Server Error.

Electronic Mail (Email)

Email is one of the oldest and most widely used internet services.

Protocols:

• SMTP — sending email.
• IMAP — reading email and syncing across devices.
• POP3 — downloading email to a single device.

Popular providers: Gmail, Outlook, Yahoo Mail, ProtonMail.

File Transfer Protocol (FTP)

FTP transfers files between computers over a network. SFTP and FTPS are secure versions. Used for hosting websites, sharing large files, backups.

World Wide Web (WWW)

The WWW is the collection of web pages and resources accessible through the internet. Each page has a URL like https://example.com/page.

Web standards:

• HTML — structure of the page.
• CSS — visual styling.
• JavaScript — interactivity.

Browsers used to view it: Chrome, Firefox, Safari, Edge.

Search engines

A search engine indexes web pages and helps users find them.

Popular search engines:

• Google — by far the most used.
• Bing — Microsoft.
• DuckDuckGo — privacy-focused.
• Yandex, Baidu — Russia, China.

They work by:

1. Crawling the web with bots.
2. Indexing the content found.
3. Ranking results using algorithms (PageRank, ML).

E-commerce

E-commerce is buying and selling goods or services over the internet.

Types:

• B2C — Amazon, Daraz, Flipkart.
• B2B — Alibaba, supplier portals.
• C2C — eBay, OLX, Hamrobazar.
• C2B — Upwork, Fiverr.

Components: product catalogue, shopping cart, checkout, payment gateway, order management, delivery.

M-commerce

Mobile commerce is e-commerce done on mobile devices. With smartphones dominating internet use, mobile-first design has become essential. Examples: shopping on the Amazon app, ordering food on Foodmandu / Pathao Food.

E-payment

Electronic payment systems include:

• Cards — credit and debit.
• Net banking — online via bank portals.
• Mobile wallets — eSewa, Khalti, IME Pay, PayPal, Google Pay.
• UPI — instant transfers in India.
• Cryptocurrency — Bitcoin, Ethereum.

E-governance

E-governance is the use of IT to deliver government services online.

Examples:

• Online filing of taxes.
• Online passport / driving licence applications.
• E-voting (in some countries).
• Citizen portals (e.g. Nagarik App in Nepal).

Censorship and privacy issues

The internet raises serious concerns:

• Censorship — some governments block certain content or websites.
• Privacy — tracking, data collection by big tech.
• Data breaches — exposing user information.
• Surveillance — by governments and corporations.

Tools that help: HTTPS, VPNs, end-to-end encryption (Signal, WhatsApp), privacy laws (GDPR in EU).

Digital divide

The digital divide is the gap between those who have easy access to the internet and those who don’t. Causes:

• Economic — cost of devices and connections.
• Geographic — rural areas with no coverage.
• Educational — lack of digital literacy.
• Age — older adults less comfortable with technology.

Bridging the divide requires affordable devices, better infrastructure, and digital literacy programs.