There is only one file type that uses the .WIM extension:
Windows Imaging Format File
A WIM file is saved in a file-based imaging format that was introduced with Windows Vista. It allows a single disk image to be deployed to multiple computer platforms. WIM files are used to manage files such as drivers, updates, and components without booting the operating system image.
WIM images may contain multiple disk images that can be mounted as new volumes within Windows. They can also be made bootable, which means a computer can boot from the disk image.
Updated: September 19, 2017