What Is HTML (HyperText Markup Language)?

What Is a Markup Language?

A markup language is a set of rules that can be processed by a computer connected with a given computer document file and dedicated - among others - to the following aspects:

  • presentational - presenting the document in a certain visual way to the end human user,

  • semantic - describing the document in a certain semantic way to computer programs reading the document enabling those programs to better understand the document (e.g. better understanding of the document by web crawlers enhancing search engine optimization).

HyperText Markup Language (HTML) is a standard markup language.

Currently the presentational aspects of HTML give way to using the Cascading Style Sheets. Further, given that the semantic aspects are getting more and more important - as they may increase search engine optimization (SEO) - using HTML for controlling visual aspects is even frowned upon as it might hinder the said optimization.

Inception & Development

HTML was first proposed in 1989 by Sir Tim Berners-Lee who in 1990 created the first HTML browser and server software. HTML was always closely related to XML. In the period from the year 2000 until the release of HTML5 in 2008 HTML was based on XML and even called XHTML (for Extensible HyperText Markup Language).

The notable differences between HTML5 and XML is that:

  • some HTML5 elements can be unclosed but XML enforces tag closing,

  • when it comes to element names and attributes HTML5 is case-insensitive but XML is case-sensitive,

  • an HTML5 parse error does not abort processing by the HTML5 parser but XML parse error aborts processing by the XML parser.


Most often HTML documents are received from remote hosts using Hypertext Transfer Protocol (HTTP). HTTP is a protocol that specifies communication rules and interface methods used by host computers in the World Wide Web communication system. The secured variant of HTTP is HTTPS

World Wide Web is an information system in which documents - including among others HTML documents - and other web resources are identified by URLs i.e. Uniform Resource Locators. Over the Internet, such resources can be accessed using computer programs such as - among others - web browsers.

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