The file extension DOCX is the latest version of the Microsoft Word doc file format. The DOCX format will be supported starting with the 2007 version of the worldwide word processing program. The file extension DOCX simply means Document Xml, ie a document in XML format.
A DOCX file contains, as well as the old doc files in addition to texts and formatting instructions also pictures and graphics. It can not contain macros. Files with macros automatically receive the extension docm.
DOCX is an XML based file format (Office Open XML) that is not legible with older versions of Word. For the Office versions 2000, 2003 and XP, however, this functionality can be retrofitted using the Microsoft Office Compatibility Pack, whereby the result of a read-in DOCX file does not always have to be 100% identical to the original.
Office Open XML is an open standard developed by Microsoft for office applications, which is intended to ensure the file exchange between different office suites.
A DOCX file consists of several XML files, which are automatically summarized as archives when saved using the ZIP algorithm. This saves space compared to the old format. Other benefits include better data integrity and easier data recovery in the event of data loss.