Overview of HTTP, HTML, WWW and web technologies.
The combo HTTP and HTML is the foundation of the World Wide Web (WWW).
HTML (HyperText Markup Language) defines a text-based format for describing the contents of a web page. HTML is based on tags similar to XML (eXtensible Markup Language), but its definition is less strict.
HTML pages are transported with the HTTP protocol (HyperText Transmission Protocol) over TCP/IP based networks.
The power of the WWW comes with the links based on URLs (Uniform Resource Locators) that connect pages to form a web of content.
Browsers display links as clickable items that, when clicked, trigger the browser to load the web page pointed to by the link.
This statelessness contributed a lot to the stability and scalability of the world wide web where web servers are only tasked with the delivery of web pages while the browser is responsible for the rendering of web pages.
The static nature of the early World Wide Web was soon augmented with the dynamic creation of web pages by web servers or by enriching static web pages with dynamic content.
Technologies like CGI (Common Gateway Interface), JSP (Java Server Pages) or ASP (Active Server Pages) were developed to provide the infrastructure to build dynamic web applications.
Web page caching is an important mechanism to reduce latency in loading web pages and reducing network traffic.
HTTP defines different caching control mechanisms. Simpler caching methods are based on web page expiry dates while more complex mechanisms use web page validation.