DITA (Darwin Information Typing Architecture) is an XML-based architecture for authoring, producing, and delivering technical information. The architecture and a related DTD and a W3C-Schema was developed by IBM.
The entire name of the architecture has this combined explanation:
Darwin: it uses the principles of specialization and inheritance
Information Typing: it capitalizes on the semantics of topics (concept, task, reference) and of content (messages, typed phrases, semantic tables)
Architecture: it provides vertical headroom (new applications) and edgewise extension (specialization into new types) for information
Unlike book-oriented approaches that are based on chapters and pages, DITA uses topics - small chunks of information that can be easily reused across various contexts and deliverables. DITA also has built-in extensibility support, meaning you can customize document type definitions (or DTDs) without breaking compatibility with existing applications and processes. For these reasons and more, DITA goes beyond any previous approach in helping you overcome barriers to XML adoption, maximize content reuse, and reduce information redundancies.
DITA specifies a number of topic types, such as Task, Concept and Reference. Within DITA, a Task topic is intended for a procedure describing how to accomplish a task; lists a series of steps that users follow to produce a specified outcome; identifies who does what, when, where and how. A Reference topic is for topics that describe command syntax, programming instructions, other reference material; usually detailed, factual material.