On the Web, a document is the unit by which information is stored and retrieved. At any one time, only a single document or a Web page, as it is fondly called, is loaded onto the reader’s computer.

It is also normally the amount you edit at any one time, though with a good editor and enough computer memory, you can have a number of documents open at a time.

If it were on paper, the size of the medium affects how content would break into pages and, hence, the number of pages a finished work can have. We tend to refer to a three-page A4-sized letter, for instance, as one document.

In the online medium, though, the concept of page breaks does not exist. A hypertext document’s “page” length is decided by the document’s content, meaning however short or long, hypertext content is rendered as one continuous page.

A document then, in the online case, refers to a single whole page that is stored and retrieved as a single file.

Whilst it is possible in online documentation to write everything into one document, you need not to, for organization and ease of navigation.

Typically, you will be writing a separate file for each topic. These files will be linked to each other, and, as hypertext is potentially unconstrained, you can link to external resources as well to extend your documentation.