Docbook is a way of writing technical documents using an XML-based markup language. With Docbook, you can create reports, books, articles and many other types of documents. It is used by many big companies and organizations like the US Navy and Microsoft, who need to write complicated documentation. In Docbook, you use a special type of code to define the elements like the text, headings, and images that appear in the document. The code looks like a combination of words in brackets, and looks a bit like a puzzle! Once the document is written, it can be converted into different formats like HTML, PDF, or eBooks.