The file extension of MS-Word document in Office 2007 is _______.

Concept

A filename extension identifies the format in which an application stores a file.

Microsoft Word uses different document formats across Office generations: the older binary format and the newer Office Open XML format have different extensions.

Application

Office 2007 uses the Office Open XML format for a standard Word document. A Word document saved in that format carries the .docx extension.

Contrast

• .pdf denotes Portable Document Format, which is intended for fixed-layout document sharing.

• .doc denotes the older binary Microsoft Word document format associated with Word 97–2003.

• .txt denotes plain text without the structured Word document package.

Therefore, the required file extension is .docx.