docx In an effort to create an open document standard, Microsoft in collaboration with ISO/IEC and Ecma, developed the Office Open XML standard in 2006. One of the filename extensions supported in this specification is the .docx extension, a text document filename extension. The .docx was introduced in Microsoft Office Word 2007 and has been supported ever since in later iterations. It has become the default filename extension for all text documents produced using Microsoft Office Word. Given the open source nature of the XML specification, more alternative document processing applications support read and write capabilities on documents saved with the .docx filename extension. This is in comparison to the .doc filename extension which is a proprietary asset owned by Microsoft.
odt The Open Document Text filename extension format is an alternative open source document and text processing file format allowing users to create text documents that can be opened and edited by an extensive list of document processing applications. Both proprietary applications (such as in Microsoft Office word) and open source document processing applications (such as OpenOffice) support the .odt filename extension allowing for interoperability between software systems. The format is useful to those creating documents meant to target a wide audience and not necessarily an audience with a specific document processing suite. The extension was first released in 2005.