How web pages work

What is The Internet

The Internet is a global network of computer (and other devices) networks that can communicate between them through the TCP/IP protocol.

Full Internet map of 29 June 1999. Antoniou, Pavlos & Pitsillides, Andreas. (2007)

It is mainly used for accessing resources (and services) such as hypertext documents of the World Wide Web, electronic mail, various files, or data streams.

Given its high complexity global reach, it doesn't have a single centralized governance. This means that if a certain component (network or computer) becomes unavailable, the Internet as a whole doesn't collapse.

WWW

The World Wide Web, or The Web, is a colossal evergrowing collection of documents interconnected via the Internet, that are identifiable through Uniform Resource Locators (URLs, such as http://google.com/) and accessible through HTTP.

HTTP

Stands for Hypertext Transfer Protocol and it is an application layer protocol, part of the TCP/IP suite and it is used by Web Servers to communicate to Web Browsers (and other client applications).

It has been initiated by Tim Berners-Lee in 1989, a moment called by many the beginning of the Internet.

HTTP follows a classical client-server model, with a client opening a connection to make a request, then waiting until it receives a response.

Example structure of a HTTP request

Web servers, Web browsers, and DNS Servers

Web servers generate HTTP responses while Web browsers initiate HTTP requests and interpret HTTP responses.

A simplified interaction between a Web browser and a Web server

HTTP/2, finalized in 2015, brought significant improvements to website performance and efficiency over its predecessor, HTTP/1.1. The key advancements include multiplexing, allowing multiple requests and responses to occur simultaneously over a single connection, and header compression, reducing overhead. It also introduced server push, enabling servers to proactively send resources to the client before they're even requested. These enhancements result in faster page load times, reduced latency, and better resource utilization.

WebSockets - a different protocol used in web technologies

Persistent connection: WebSockets establish a persistent, two-way connection between the client and server. Once the connection is established, both parties can send data at any time.

Stateful: WebSockets maintain state, meaning the server can keep track of the client's connection and any data that has been exchanged.

Full-duplex: Communication is full-duplex, allowing both the client and server to send data simultaneously.

Ideal for: Real-time applications like chat, online games, live updates, and collaborative tools where instant communication is crucial.

DNS stands for Domain Name System and is basically a systemized way to label computers and other devices over the Internet or private networks making them identifiable via a Domain Name rather than through a unique IP address.

In reality, this interaction is a multi-step process as shown below:

The Domain Name System (DNS) is like a global phonebook for the internet, translating human-readable domain names (like google.com) into machine-readable IP addresses. Its maintenance is a shared responsibility. At the top level, the Internet Corporation for Assigned Names and Numbers (ICANN) oversees the root servers and delegates authority for top-level domains (like .com, .org) to registries. These registries then work with registrars (companies like GoDaddy or Namecheap) who sell domain names to individuals and organizations. Finally, website owners manage the DNS records for their specific domains, specifying how their domain name maps to their web server's IP address. This distributed system ensures redundancy and resilience, keeping the internet running smoothly.

Web Pages

Web pages are (basically) documents formatted with HTML and can be optionally packed with styling guides (CSS files), behavior (Javascript files), and multimedia (images, audio, video files).

FrontEnd vs. BackEnd

FrontEnd refers to the source code (received as a plain answer from HTTP requests) which a browser can interpret.

BackEnd is the source code executed at a Web Server level, and cannot be accessed by the browser. It is typically used for generating HTTP responses, interacting with Databases or other Information Systems, and for performing various other logical tasks.