HTML stands for HyperText Markup Language ("markup language hypertext"), refers to the markup language for web development. It is a standard that serves as a reference for the development of websites in different versions, defines a basic structure and code (called HTML) to define the content of a website, such as text, images, and more. It is a standard by the W3C, an organization dedicated to the standardization of almost all web-related technologies, especially about their writing and interpretation. A web browser can read HTML files and compose them into visible or audible web pages. The browser does not display the HTML tags, but uses them to interpret the content of the page. HTML describes the structure of a semantic web site along with the signals for the presentation, so it is a markup language rather than a programming language.
Extensible Markup Language (XML) is a markup language that defines a set of rules for encoding documents in a format which is both human-readable and machine-readable. It is defined by the W3C's XML 1.0 Specification and by several other related specifications, all of which are free open standards. The design goals of XML emphasize simplicity, generality and usability across the Internet. It is a textual data format with strong support via Unicode for different human languages. Although the design of XML focuses on documents, it is widely used for the representation of arbitrary data structures such as those used in web services. Several schema systems exist to aid in the definition of XML-based languages, while many application programming interfaces (APIs) have been developed to aid the processing of XML data.