This section describes some of the commonly used formats for documentation files and discusses the strengths and weaknesses of each file format. Some formats (such as XML) are more common as source formats—that is, the files where the raw content is added. Other formats (such as PostScript and PDF) are more often used as release formats—that is, the files that are available for customers to use. Only a few formats (such as raw text files) are used as both source and release file formats.
Current best practice is to provide documents as both HTML web pages (for fast access) and PDF (for downloading complete documentation packages and for printing). It's helpful if you provide a single web page where all the different formats for your documentation can be downloaded, so that people only have to refer to a single URL. For example, http://www.example.com/myproduct/docs, not http://www.example.com/myproduct/pdf/manual and http://www.example.com/myproduct/html/manual.
Some common requirements of a file format and the tools that support it are:
Typeset printing, often using different file formats, sizes, and layouts
Online viewing, often with hyperlinks
Images interleaved with text
Searching documents for text or formatting
Support for non-English languages and characters
Comments that can be mixed with text for reviews but that don't appear in the final product
Joining and splitting files
Generating lists of the differences between versions of the document, or ...