A document file format is a text or binary file format for storing documents on a storage media, especially for use by computers. There currently exist a multitude of incompatible document file formats.

Examples of XML-based open standards are DocBook, XHTML, and, more recently, the ISO/IEC standards OpenDocument (ISO 26300:2006) and Office Open XML (ISO 29500:2008).

In 1993, the ITU-T tried to establish a standard for document file formats, known as the Open Document Architecture (ODA) which was supposed to replace all competing document file formats. It is described in ITU-T documents T.411 through T.421, which are equivalent to ISO 8613. It did not succeed.

Page description languages such as PostScript and PDF have become the de facto standard for documents that a typical user should only be able to create and read, not edit. In 2001, a series of ISO/IEC standards for PDF began to be published, including the specification for PDF itself, ISO-32000.

HTML is the most used and open international standard and it is also used as document file format. It has also become ISO/IEC standard (ISO 15445:2000).

The default binary file format used by Microsoft Word (.doc) has become widespread de facto standard for office documents, but it is a proprietary format and is not always fully supported by other word processors.