A markup language provides a way to combine a text and extra information about that text. The extra information, such as structure or layout, is expressed using markup, which is typically intermingled with the primary text. The best-known markup language in modern use is HTML (HyperText Markup Language), which is one of the foundations of the World Wide Web.
Originally, markup was used in the publishing industry in the communication of printed work between authors, editors, and printers.
HTML is not the only markup language; other languages such as XHTML (Extensible Hypertext Markup Language) and XML (Extensible Markup Language) are examples of other widely used markup languages.