In technical communication, topic-based authoring is a modular approach to content creation where content is structured around topics that can be mixed and reused in different contexts. It is defined in contrast with book-oriented or narrative content, written in the linear structure of written books. Topic-based authoring is popular in the technical publications and documentation arenas, as it is especially suitable for technical documentation. Tools supporting this approach typically store content in XHTML or other XML formats and support content reuse, management, and the dynamic assembly of personalized information. A topic is a discrete piece of content that: * focuses on one subject * has an identifiable purpose * does not require external context to understand Topics can be written to be independent of one another and reused wherever needed. The Darwin Information Typing Architecture is a standard designed to help authors create topic-based structured content. The standard is managed by the Organization for the Advancement of Structured Information Standards DITA Technical Committee.