Apple TextEdit is a text editor program and an open-source word processor too, which is first used in NeXTSTEP and OPENSTEP, but now integrated in most recent versions of Mac OS X. It is also considered a GNUstep application for other operating systems that are Unix based, like Linux computers. This program is operated by Advanced Typography by Apple so expect several advanced typography related features. The main function of this software is to read and write documents in plain text, HTML formats, Rich Text Format, and Rich Text Format Directory. It can also open Simple Text files but does not have the capability to save documents of that format. Mac OS X version 10.3 supports Microsoft Word documents, while Mac OS X version 10.4 can open and save Word documents in XML file. Mac OS X version 10.5 is able to read and write Office Open XML as well as OpenDocument Text. Features included on TextEdit are formatted text support, addition of graphics, animations and other multi-media contents, automatic adjustment of letter spacing, as well as reading and writing support of character encodings.