Files with the WBK extension are documents created by Microsoft Word, the word processor included in Microsoft Office. WBK stands for "Word Backup". These files are used as temporary backups and are automatically created by Word every time a new document is opened. In case the application crashes or is closed unexpectedly, users can recover their unsaved documents by opening the WBK files. The automatic backup process can be enabled or disabled by accessing the Advanced Word Options and selecting or deselecting "Always create backup copy".

Just like normal Microsoft Word documents, WBK files can contain various elements such as images, drawn objects, tables, links to websites and links to other local files. The text formatting options and styles of the original document are also preserved.

The WBK file format was first introduced in Word 2010 and it is still being used as the default backup format.

How to open WBK files

Following a crash or an unexpected system error, backup files are automatically displayed by Microsoft Word when running it for the first time. Saved documents can be selected from the panel on the left. WBK files can also be opened manually with Microsoft Word.