Lecture 2 Notes – The Internet & World Wide Web

Objectives (Lecture 2)

  • Understand the historical evolution, current architecture, and governance of the Internet.
    • From 1969 ARPANET to today’s multi-billion-node global network.
    • Roles of bodies such as ARPA, NSF, W3C, Internet2.
  • Distinguish broadband connections from dial-up and list all modern broadband media.
  • Classify Internet access providers (ISP, OSP, wireless ISP).
  • Explain IP addressing, domain names, and DNS translation.
  • Identify Web browsers, parse Web addresses (URLs), and recognise each component.
  • Use search tools efficiently; differentiate search engines from subject directories and apply operators to refine queries.
  • Catalogue the 13 distinct Web-site categories and the complete multimedia tool-set (graphics, animation, audio, video, VR, plug-ins).
  • Outline the five-step Web-publishing cycle.
  • Differentiate e-commerce flavours (B2C, C2C, B2B; plus m-commerce).
  • Describe auxiliary Internet services: e-mail, mailing lists, IM, chat, VoIP, newsgroups, message boards, FTP.
  • Adhere to netiquette.

The Internet: Definition & Scope

  • A worldwide, publicly accessible collection of interconnected networks linking millions of businesses, governments, schools, and individuals.
  • Key requirement: packet switching allows communication to continue even if segments are destroyed.

Historical Milestones

  • 1969: ARPANET functional; two goals:
    • Share research data among geographically distant scientists.
    • Survive partial network failure.
  • 1984: >1{,}000 host computers online.
  • 1986: NSF links NSFnet with ARPANET ⇒ term “Internet”.
  • 1995: NSFnet reverts to research role; commercial traffic dominates Internet.
  • 1996: Internet2 founded (today connects 200+ universities & 115 corporations on high-speed backbone).
  • Today: >550 million hosts; autonomous management—each organisation maintains its own sub-network.

Governance & Standards

  • No central owner; coordination via:
    • W3C (World Wide Web Consortium): sets Web standards (HTML, CSS, accessibility).
    • IETF/ICANN: manage protocols, IP address allocation, domain registry.

Connecting to the Internet

Broadband vs Dial-Up

  • Broadband = high-speed (≥256 kbps) always on; dial-up = temporary, analog 56 kbps max.
  • Types of broadband access:
    • Cable Internet (coax shared by ≈500 homes).
    • DSL (digital signal over copper telephone lines).
    • FTTP/FTTH (pure fibre optic to premises).
    • Fixed wireless (directional dish antenna to ISP tower).
    • Cellular radio (3G/4G/5G built-in modem or hotspot).
    • Wi-Fi hotspots (radio 2.4 / 5 GHz).
    • Satellite (geostationary; higher latency).

Access-Provider Taxonomy

  • ISP: primary Internet Service Provider (regional vs national).
  • OSP: Online Service Provider (value-added portals)—e.g.
    • AOL, MSN—bundled news, e-mail, IM, cloud storage.
  • Wireless ISP (WISP): supplies hotspot/cellular data (e.g., Surfline).

Data-Flow Example (Cable Modem)

  1. User triggers request (e.g., clicks URL).
  2. Cable modem converts PC’s digital signals; coax carries them to central cable system.
  3. Central system → fibre backbone → ISP router.
  4. ISP forwards via Internet backbone to target server.
  5. Server sends HTML back along same path.

Addressing & Naming

  • IP address: unique 32-bit (IPv4) or 128-bit (IPv6) number; example 216.58.192.142 (Google).
  • Domain name: human-readable alias (www.google.com).
    • Top-Level Domains (TLDs): .com, .edu, .gov, .mil, .biz, .mobi , etc.
    • DNS server performs bi-directional translation.
  • Generic TLD snapshot:
    • .aero (aviation), .biz (business), .cat (Catalan culture), .pro (licensed professionals), .travel (travel industry), etc.

World Wide Web Fundamentals

  • Web = global collection of hyperlinked electronic documents (Web pages).
  • Web site: logically related set of pages/files; delivered by a Web server.
  • Web 2.0: platforms enabling user-generated content, collaboration (wikis, social media, blogs).
  • Home page: default landing document for a site.

Web Browsers & Rendering Cycle

  1. Start browser (Chrome, Edge, Firefox, Safari, Opera).
  2. Browser checks home-page URL (e.g., msn.com).
  3. ISP’s DNS resolves domain to IP.
  4. Browser sends HTTP/S GET to Web server; server returns HTML/CSS/JS; browser renders.
  • Tabbed browsing: multiple pages in one window, each tab with separate process/thread.
  • Downloading: transfer from remote server → local device (contrasts with uploading).
  • Microbrowser: stripped-down browser for small screens (feature phones, wearables).

URL Anatomy

  • General syntax: \texttt{protocol://host_name/path?query#fragment}
    • Protocol examples: http, https, ftp, mailto, file.
    • Example: https://en.wikipedia.org/wiki/Internet.

Searching the Web

Tools

  • Search Engine: crawls & indexes billions of pages; returns ranked hits (Google, Bing, Baidu, DuckDuckGo).
  • Subject Directory: human-curated hierarchy (DMOZ/Open Directory, Yahoo! Directory).

Common Operators

  • Space or + => logical AND (art + music).
  • OR => logical OR (dog OR puppy).
  • Parentheses group logic (pizza OR subs) Kalamazoo .
  • Minus sign - excludes term (automobile -convertible).
  • Quotes " " enforce exact phrase ("19th century literature").
  • Asterisk wildcard (writer ⇒ writer, writers, writer’s).

Instant Search Box

  • Modern browsers integrate omnibox/combined address bar—send keystrokes directly to default engine.

Thirteen Types of Web Sites

  1. Portal (Yahoo!, MSN).
  2. News (BBC, CNN).
  3. Informational (CDC, weather.com).
  4. Business/Marketing (corporate presence).
  5. Blog (WordPress blogs, Blogger).
  6. Wiki (Wikipedia, Fandom).
  7. Online Social Network (Facebook, LinkedIn).
  8. Educational (MOOCs, university sites).
  9. Entertainment (YouTube, Netflix).
  10. Advocacy (NGOs, political campaigns).
  11. Web Application (Google Docs, Canva).
  12. Content Aggregator (Feedly, Flipboard).
  13. Personal (individual home pages, vlogs).

Content Evaluation

  • No central editor; verify authority, accuracy, objectivity, currency, coverage.
  • Cross-check citations; beware of biased advocacy pages.

Multimedia Elements

Graphics

  • Bitmap formats: BMP (uncompressed), GIF (256-color, animation support), JPEG (lossy photograph), PNG (loss-less, transparency), TIFF (archival).
  • Thumbnail = downsized preview to accelerate page load.

Animation

  • Illusion of movement via rapid display of sequential stills (GIF loops, CSS sprites, Flash/HTML5 canvas).

Audio

  • Streams (MP3, AAC, OGG) compressed to reduce bandwidth.
  • Player software (VLC, Windows Media Player) or embedded HTML5
  • Streaming delivers continuous packets; user hears early portions while later segments still downloading.
  • Example workflow: iTunes Store purchase → download → local playback or sync to iPod.

Video

  • Formats (MP4/H.264, WebM, AVI). Example: YouTube video page with embedded player, progress bar, related clips.

Virtual Reality (VR)

  • 3-D simulated environments; interaction via keyboard/mouse, sensors, head-mounted displays.

Plug-Ins / Add-Ons

  • Small helper programs (Adobe Reader for PDF, Flash Player, Unity, WebGL run-time) that extend browser capabilities.

Web Publishing Life-Cycle

  1. Plan: purpose, audience, content outline, navigation structure.
  2. Analyze & Design: storyboard, choose technologies (HTML5, CSS3, JS), accessibility compliance.
  3. Create: author pages with editor/IDE; incorporate multimedia.
  4. Deploy: upload to Web server (via FTP/SFTP); test links, compatibility.
  5. Maintain: update content, monitor analytics, patch security holes.

Electronic Commerce (E-Commerce)

  • Definition: any commercial transaction over electronic networks.
  • Categories:
    • B2C: business sells to end consumer (Amazon, Jumia).
    • C2C: consumers trade with each other (eBay, Craigslist).
    • B2B: inter-company supply chain transactions (Alibaba, SAP Ariba).
  • M-Commerce: e-commerce on mobile devices (in-app purchases, mobile wallets).

E-Retail Process Example

  1. Shopper browses e-storefront.
  2. Adds items to electronic cart.
  3. Enters payment on secure HTTPS form; data encrypted.
  4. Bank/processor authorises card.
  5. E-retailer confirms, processes order.
  6. Fulfilment centre packs & ships.
  7. Tracking information posted online.
  8. Delivery arrives; signature captured on handheld device.

Additional Internet Services

E-Mail

  • Components: user agent (client), SMTP outgoing server, POP3/IMAP incoming server.
  • Transmission path: Sender → SMTP server → Internet routers → recipient’s incoming server → recipient’s client downloads.
  • Features: compose, attach files, CC/BCC, folders, spam filters.

Mailing Lists

  • One-to-many broadcast via single list address.
  • Subscribe/Unsubscribe commands handled by list software (Listserv, Mailman).

Instant Messaging (IM)

  • Real-time text exchange; presence indicators (available/away).
  • Examples: WhatsApp Web, Slack, Microsoft Teams.

Chat & Chat Rooms

  • Live typed dialogue; may be moderated.
  • Web-based or IRC; persistence varies (some rooms retain archives).

Voice over IP (VoIP)

  • Digitises voice, encapsulates in IP packets; traverses Internet rather than PSTN.
  • Services: Skype, Zoom, WhatsApp calls.
  • Hardware: headset, microphone, webcam; QoS sensitive to latency <150 ms.

Newsgroups & Message Boards

  • Usenet hierarchical forums (comp.lang.python, sci.space). Require newsreader.
  • Modern equivalents: Reddit boards, web forums.

FTP (File Transfer Protocol)

  • Standard ports: 20 (data), 21 (command).
  • Enables upload/download; anonymous FTP allows public access.
  • Built-in OS clients (Command-line ftp, Finder, File Explorer); GUI tools (FileZilla).

Netiquette (Internet Etiquette)

  • Golden Rule: treat others online as you wish to be treated.
  • Guidelines:
    • Keep messages concise; proofread for grammar & clarity.
    • Avoid offensive language; be cautious with sarcasm.
    • Use descriptive subject lines; trim quoted material in replies.
    • NO ALL CAPS (perceived as shouting).
    • Do not post flames (abusive messages) or engage in flame wars.
    • Shun spam (unsolicited bulk mail/posts).
    • Use emoticons :-) and acronyms (btw, imho, fyi) judiciously.
    • Mark spoilers clearly.
    • Read site FAQ before posting; forgive honest mistakes.
    • Respect privacy—never read others’ e-mail without permission.

Summary / Takeaways

  • Internet progressed from ARPANET \rightarrow NSFnet \rightarrow current heterogeneous network of >550 million hosts.
  • Web operates on top of Internet, adding URLs, HTTP/S, browsers, search tools, and interactive Web 2.0 content.
  • Broadband connectivity, DNS, and IP addressing are foundational.
  • Effective searching, critical evaluation, and comprehension of multimedia enrich Web usage.
  • Web publishing follows a structured lifecycle; e-commerce leverages secure, end-to-end online workflows.
  • Auxiliary services (e-mail, IM, FTP, VoIP) expand communication/toolset.
  • Observing netiquette ensures respectful, efficient, and secure online interactions.