What does mark up mean in HTML?

@Sam Hobbs

Thanks for replying.. Please share your knowledge about mark up language. Many people don`t know what exactly it means.. Waiting for your article.

Thanks once again for all who replied..:)

See Proofreading in printing and publishing. The term markup language seems to be based on what proofreaders do; they mark up a document.

Originally HTML did not have scripts. It was just a way to provide formatting for documents. In word processing software such as Word, documents were stored with binary data to specify formatting, such as what font to use. HTML and XML are a SGML application. SGML is a word processing language. SGML provides a way to specify tags that can represent the format of a document, similar to what Word documents do, except in SGML, HTML and XML, the tags are in a text format whereas in most other word processing software, the formatting codes are stored in a binary format. So originally at least, the markup language part of the name Hypertext Markup Language (HTML) was essentially a way to specify formatting in a non-binary format. So when Vulpes says that they are languages, note that most word processing software store formatting in a similar manner, except most word processing software use binary codes instead of text codes. In a corresponding manner, XML is a way to store data using text codes (ML) to specify the format of the data.

I will some day write an article revealing some secrets about ML that very few people know.