Chapter 2 The World Wide Web


Internet vs Web

  • Interent: The global physical network of computers routers cables and other data wireless streamed devices

  • World wide web (web): Software layer on top of the internet that links documents and resources using URLS, HTTPs and HTMLs

Key Historical Events

  • 1989: Tim Berners‑Lee proposed the Web at CERN to enable sharing hyperlinked documents across different systems.

  • 1990–1991: First Web server and (text-based) browser prototypes; Berners‑Lee made the system freely available.

  • 1993: Mosaic (graphical browser) made the Web widely usable; led to explosive growth.

  • Mid‑1990s onward: Netscape, Internet Explorer, later Chrome; introduction of JavaScript (dynamic pages) and Web 2.0 concepts.

  • Standards and governance: W3C (World Wide Web Consortium) leads HTML, HTTP and related standards (https://www.w3.org).

How the Web works

  1. Athorrizing: the web page is written up as a HTMLdocument (plain text with markup tags describing structure and formatting

  2. Publishing: HTML file is placed on a web Server (a maciine running software that respponds to requests)

  3. Addressing: Each resource is given a URL (uniform resource locater) so browsers can locate it

  4. Requests/Responses: A users web browser sends a HTTP request to the server and the page responds with the page and headers

  5. Rendering: Browser interprets HTML, CSS and Javascript and displays the page; embeded resources (images, scripts and video) trigger further HTTP requests.

  6. Optimization: Browsers use caching to store copies of resources locally and cookies to store small data items for site-specific state.


  • World Wide Web (Web): A distributed system of interlinked documents and resources accessed over the Internet using URLs, HTML and HTTP.

    • Example: Visiting https://www.example.com to read an article.

  • Internet: The global physical network of computers and devices that carry packets of data via protocols such as TCP/IP.

    • Example: Your home router connects your laptop to the wider Internet through your ISP.

  • Hypertext: text that contains links to other texts or resources

    • example: a wikipedia article with blue text

  • HTML (Hypertext markup language): the standerd text used to structure content on web pages

  • HTTP (hypertext transfer protocall): protocal used for transfering web pages from browser to server (commands like GET, POST).

  • HTTPS: secure HTTP over TLS or SSL

  • URL (uniform resource locater): address used to indetify web resource; includes protocal, server name and path

  • web server: software that stores resources and respodsn to HTTP requests

  • web browser: client server then reqeusts, recieves and renders web pages

  • web crawler/spider: automated service that transverses the web, following llinks to discover and index pages for search engines

    • example: google bot visits pages to add them to google index

  • Pagerank: made by brin and page that ranks pages by link-based importance

  • Cache/caching: temporary storage of previously fetched resoruces to avoid redownload

  • Cookie: small data file a server asks the browser to store and send back on subsequent requests to the same site; used for session state, prefereance and shopping cart.

  • ISP (internet service provider): company that provides internet connectivity and some hosting and web server space

    • comcast at&t or local hosting providers

  • web hosting provider: a company that runs service and rents space or service to hosting websites

  • Web 2.0: a broad descripter towards teh webs evolution toward interactive dynamic user faced content

    • Example: Social networks, single-page apps, and sites that let users edit content.

  • network effect: when a product becomes more valuable as mroe people use it

  • W3C (worldwide web consortium): the organizaiton that mantains web standerds (HTML, CSS, accessibility specs).