A Docx file is a Microsoft Word Open XML Format Document file. This kind of file is used for everything from resumes and cover letters to reports, flyers, documentation, invitations, newsletters, and more. The Docx file usually contains text but can also include objects, styles, rich formatting, and images. Docx files can be opened with Word 2007 and lateral versions but not with the earlier versions of Microsoft Word which still supports Doc file extensions.