This article describes the technical specifications of the OpenDocument office document standard, as developed by the OASIS industry consortium. A variety of organizations developed the standard publicly and make it publicly accessible, meaning it can be implemented by anyone without restriction. The OpenDocument format aims to provide an open alternative to proprietary document formats.

The OpenDocument format supports the following two ways of document representation:

The recommended filename extensions and MIME types are included in the official standard (OASIS, May 1, 2005, and its later revisions or versions). The MIME types and extensions contained in the ODF specification are applicable only to office documents that are contained in a package. Office documents that conform to the OpenDocument specification but are not contained in a package should use the MIME type text/xml.

The MIME type is also used in the office:mimetype attribute. It is very important to use this attribute in flat XML files/single XML documents, where this is the only way the type of the document can be detected (in a package, the MIME type is also present in a separate file mimetype). Its values are the MIME types that are used for the packaged variant of office documents.

The most common file extensions used for OpenDocument documents are .odt for text documents, .ods for spreadsheets, .odp for presentation programs, and .odg for graphics. These are easily remembered by considering ".od" as being short for "OpenDocument", and then noting that the last letter indicates its more specific type (such as t for text). Here is the complete list of document types, showing the type of file, the recommended file extension, and the MIME Type:

OpenDocument also supports a set of template types. Templates represent formatting information (including styles) for documents, without the content themselves. The recommended filename extension begins with ".ot" (interpretable as short for "OpenDocument template"), with the last letter indicating what kind of template (such as "t" for text). The supported set includes:

As noted above, the OpenDocument format can describe text documents (for example, those typically edited by a word processor), spreadsheets, presentations, drawings/graphics, images, charts, mathematical formulas, and "master documents" (which can combine them). It can also represent templates for many of them.

The official OpenDocument standard version 1.0 (OASIS, May 1, 2005) defines OpenDocument's capabilities. The text below provides a brief summary of the format's capabilities.