World Wide Web

Berners-Lee's Vision

While ARPANET connected computers, Tim Berners-Lee wanted to connect information. Working at CERN, he proposed a system where documents could link to other documents anywhere on the network—a "web" of knowledge. His invention combined three technologies:

• HTML: HyperText Markup Language for creating documents
• URL: Uniform Resource Locator for addressing documents
• HTTP: HyperText Transfer Protocol for fetching documents

The First Website

On August 6, 1991, info.cern.ch became the first website. It explained what the World Wide Web was and how to use it. The browser was called WorldWideWeb (later Nexus). By the end of 1991, several other sites had appeared, and the web was born.

HTTP: The Protocol That Carries the Web

HTTP (HyperText Transfer Protocol) is the application-layer protocol that powers every web page load. Its evolution tracks the web's growth from simple document retrieval to complex application delivery.

HTTP/1.0 (RFC 1945, 1996)

The original HTTP established a new TCP connection per request. For a page with 20 images, the browser needed 21 separate TCP handshakes — each adding 1-RTT latency. This request-response model was simple but wildly inefficient. Each connection consumed server resources and added round-trip delays.

HTTP/1.1 (RFC 2068, 1997; RFC 2616, 1999)

HTTP/1.1 introduced persistent connections (keep-alive) by default, allowing multiple requests over a single TCP connection. It added pipelining (sending multiple requests without waiting for responses), chunked transfer encoding(sending data in pieces), and host headers(virtual hosting — multiple domains on one IP). These improvements reduced latency but couldn't eliminate head-of-line blocking at the TCP level.

HTTP/2 (RFC 7540, 2015)

HTTP/2 was a paradigm shift: binary framing replaced text-based headers, and multiplexing allowed multiple streams over a single TCP connection. A browser could now request 100 resources simultaneously without waiting for each to complete. Key features include:

• Header Compression: HPACK compression reduces redundant header overhead
• Server Push: Server proactively sends resources the client will need
• Stream Prioritization: Client hints which resources are most important
• Binary Protocol: More efficient parsing than HTTP/1.1 text format

Despite multiplexing, HTTP/2 still suffered from TCP-level head-of-line blocking — a single lost packet stalled all streams on that connection.

HTTP/3 (RFC 9114, 2022)

HTTP/3 solves head-of-line blocking by replacing TCP with QUIC (Quick UDP Internet Connections) running over UDP. QUIC was designed by Google (originally for SPDY) and standardized by the IETF. Key innovations:

• 0-RTT Connection Establishment: On reconnect, data can be sent immediately using cached cryptographic parameters — no round-trip wait
• Built-in TLS 1.3: Encryption is mandatory, not optional as in HTTP/2
• Independent Streams: Each stream has its own loss recovery — one lost packet only affects one stream
• Connection Migration: Connections survive network changes (e.g., Wi-Fi to cellular) using connection IDs instead of IP tuples

TLS 1.3: Securing the Web

Transport Layer Security (TLS) encrypts web traffic. TLS 1.3 (RFC 8446, 2018) reduced the handshake from 2-RTT (TLS 1.2) to 1-RTT, and supports 0-RTTresumption. It mandates AES-256-GCM and ChaCha20-Poly1305as the only cipher suites, eliminating hundreds of weak or legacy algorithms. The full handshake is now just one round trip:

1. Client Hello: Client sends supported cipher suites, key share, and SNI (Server Name Indication)
2. Server Hello: Server selects cipher suite, sends its key share and certificate
3. Finished: Both derive session keys from the ephemeral key exchange (ECDHE). Encryption begins immediately.

DNS: The Internet's Phone Book

Before a browser can load a page, it must resolve the domain name to an IP address through a chain of DNS servers:

1. Recursive Resolver: Your ISP's DNS server (e.g., 8.8.8.8 for Google, 1.1.1.1 for Cloudflare) receives the query and does the heavy lifting
2. Root Servers: 13 root server clusters (A through M) direct the resolver to the appropriate TLD server
3. TLD Servers: Manage top-level domains (.com, .org, .uk) and point to authoritative servers
4. Authoritative Servers: The final DNS server that holds the actual A/AAAA records for the domain

Each step adds latency (typically 5-20ms per hop). DNS caching at multiple levels — browser, OS, router, ISP — dramatically reduces this overhead. DNS over HTTPS (DoH) and DNS over TLS (DoT) encrypt DNS queries to prevent eavesdropping and manipulation.

HTML5: Native Web Platform

HTML5 (finalized 2014) turned the browser into a full application platform with native elements that eliminated the need for plugins like Flash:

• <video> and <audio>: Native media playback with codec support (H.264, VP9, AV1)
• <canvas>: 2D and WebGL 3D graphics rendering
• <svg>: Scalable vector graphics inline in HTML
• Web Storage, IndexedDB: Client-side data persistence
• Web Workers: Background threading for computation
• WebRTC: Peer-to-peer real-time audio/video communication
• Service Workers: Offline-capable Progressive Web Apps (PWAs)

The Browser Wars

Marc Andreessen's NCSA Mosaic (1993) made the web accessible to non-technical users. He then founded Netscape, whose Navigator browser captured 90% market share by 1995. Microsoft's rushed Internet Explorer launch began the first browser war—one that Microsoft ultimately won but at the cost of web standardization suffering.

The Dot-Com Boom and Bust

By 1999, any company with ".com" in its name could command billion-dollar valuations. Pets.com, Webvan, and thousands of others burned through venture capital before collapsing in 2000-2001. Yet survivors like Amazon, eBay, and Google proved the web's fundamental commercial viability.

Web 2.0 and Beyond

The 2000s saw the rise of user-generated content: blogs, wikis, social networks. Ajax made web applications feel responsive. Mobile devices made the web accessible everywhere. Today, the web encompasses billions of pages, billions of users, and services that have become essential infrastructure.