DOC is the document file format introduced by Microsoft Word and uses the .DOC file extension. In addition to text, these files can also contain hyperlinks, images, graphics, tables, advanced formatting, and other elements.
With Microsoft Office 2007, the .DOCX file extension was introduced. It uses the Microsoft Office Open XML international standard, which makes the format more accessible and usable.
While newer versions of Microsoft Word can open the older DOC format, DOCX files cannot be opened in older versions. If they can be opened, the formatting may be incorrect or parts of the document may be missing.