DITA topics are the basic units of authoring and reuse. OASIS defines DITA topics as a unit of information with a title and content, short enough to be specific to a single subject or answer a single question, but long enough to make sense on its own and be authored as a unit. The DITA Topic is the base topic document type. The other DITA topic types are specializations of DITA Topic. DITA topics have a .dita file extension. DITA topics can also use the .xml file extension, but it is recommended that you use .dita.