There is only one file type that uses the .TEMP extension:
Temporary (Temp) File
A TEMP file is a temporary file that may be created by various software programs. It is typically generated while the program is running to temporarily store information, then is automatically deleted when the program is closed.
Common temporary files include auto-saved documents, session control lock files, cache files, and backup files. Some temporary files can be opened by the program that generated them, while others are not meant to be opened by the user.
If the program that creates a TEMP file crashes and does not delete the file, it will remain on the computer instead of being deleted. Any TEMP files left on a computer are typically deleted when rebooting the operating system. The files can also be manually deleted by a user without affecting the original file.
NOTE: Most temporary files use the .TMP file extension.
Updated: July 13, 2019