Updated: 08/16/2021 by Computer Hope
DOCX file format.

The DOCX file format is used by Microsoft Word 2007 and later versions. It uses the .docx file extension, and is designed to replace the DOC file format used in previous versions of Word.

To open a .docx file, you must use Microsoft Word 2007 or later versions. If you do not have one of these versions and still need to view a .docx file, you can download a free DocX viewer application, or a compatibility pack from Microsoft.


Earlier versions of Microsoft Word defaulted to the .doc file extension.

What is the extra "x" for?

The extra "x" in the Microsoft Office .docx, .xlsx, and .pptx file extensions indicates the files are using the XML format.

DOC, File extension, Word processor terms