DocBook is a markup language used for writing technical documentation. It allows authors to create structured documents that can be easily converted into various formats, such as HTML, PDF, and ePub. This flexibility makes it popular among technical writers and software developers. The DocBook format is based on XML, which means it uses tags to define elements like chapters, sections, and tables. This structured approach helps maintain consistency and organization in documents, making it easier for readers to navigate and understand the content.