Abbreviation. The HTML <abbr> tag is used for indicating an abbreviation.
This tag is often used in conjunction with the global title attribute in order to provide an expansion of the abbreviation. When this attribute is specified, it should only contain an expansion of the abbreviation and nothing else.
By marking up abbreviations you can give useful information to browsers, spell checkers, translation systems and search-engine indexers.
The <abbr title="HyperText Markup Language">HTML</abbr> tag.