For example, the markup language HTML, used for web pages, has been standardized by the World Wide Web Consortium. Whenever a newer version of HTML is published, W3C may decide that some old HTML style tags are not needed, since new methods exist to express the same thing. Such tags are said to be deprecated.
This means the members of W3C have decided not to guarantee their availability in future versions of HTML. Popular web browsers still understand most deprecated tags. However, a new browser may ignore them while being advertised as "HTML 4.0 compliant".
To learn more about web page (HTML) formatting, see Cascading Style Sheets
In English, the word deprecate traditionally means "to strongly disapprove" of something. It is a back-formation from deprecation, which originally meant a prayer to avert some evil or disaster. Deprecate is also used loosely, and some would say inappropriately, as a substitute for the unrelated word depreciate, which means "to esteem of little value; to reduce in price; to belittle." It is uncertain which use of the word led to its meaning in computer jargon.