A DOCX file is a document file format used by Microsoft Word which is part of the Office Open XML (OOXML) specification. However, DOC is the older binary file format used by Microsoft Word before Office 2007.

DOCX files became the standard for Word documents with the release of Microsoft Office 2007 and later versions. DOCX is XML-based and more open, facilitating easier integration.

DOC files store documents in a binary format, which is less efficient in terms of file size and compatibility compared to the newer DOCX format.