DocBook
DocBook is an XML-based markup language and schema designed for creating structured documentation, particularly for technical and software documentation. It provides a standardized set of tags for defining elements like chapters, sections, tables, and code listings, enabling content to be separated from presentation. This allows documentation to be authored once and published in multiple formats, such as HTML, PDF, and EPUB, using transformation tools.
Developers should learn DocBook when working on projects that require maintainable, scalable, and multi-format technical documentation, such as software manuals, API references, or books. It is especially useful in environments where documentation needs to be version-controlled, collaboratively edited, and consistently formatted across different outputs, as it enforces structure and facilitates automated publishing workflows.