what is the extension name of ms word 2010

The default file extension for MS Word 2010 is .docx. Word 2010 can also save in the older .doc format for compatibility with earlier versions.

File format

• .docx : Default format in Word 2010.

• .doc : Older Word format used for compatibility mode.

Simple answer

If you need the one main extension name, it is .docx.

TL;DR: MS Word 2010 uses .docx by default.