Standards

Many formal standards and other technical specifications define the operation of different aspects of the World Wide Web, the Internet, and computer information exchange. Many of the documents are the work of the World Wide Web Consortium (W3C), headed by Berners-Lee, but some are produced by the Internet Engineering Task Force (IETF) and other organizations.
Usually, when web standards are discussed, the following publications are seen as foundational:
Recommendations for markup languages, especially HTML and XHTML, from the W3C. These define the structure and interpretation of hypertext documents.
Recommendations for stylesheets, especially CSS, from the W3C.
Standards for ECMAScript, a.k.a. JavaScript, from Ecma International.
Recommendations for the Document Object Model, from W3C.
Additional publications provide definitions of other essential technologies for the World Wide Web, including, but not limited to, the following:
Uniform Resource Identifier (URI), which is a universal system for referencing resources on the Internet, such as hypertext documents and images. URIs, often called URLs, are defined by the IETF's RFC 3986 / STD 66: Uniform Resource Identifier (URI): Generic Syntax, as well as its predecessors and numerous URI scheme-defining RFCs;
HyperText Transfer Protocol (HTTP), especially as defined by RFC 2616: HTTP/1.1 and RFC 2617: HTTP Authentication, which specify how the browser and server communicate with each other.