Nothing, but as a file-extension it means backup.
The files which store the copy of your original data are called backup files. In windows backup files are created by NTbackup utility and windows backup and restore utilities. These backup files have .bkf file extension.
The is SketchUp's backup file. You will need a copy of SketchUp to view the file. If it won't open then rename the extension ".skp" and it should open.
.pfx
The olp file type (extension) was used by Microsoft for Office Live Package(?) to allow for the backup and restoring of Office Live websites.
.cer for file without private key, .pfx for file with private key
The MSBACKUP program in DOS receives its settings from the setup file. This setup file features a .set extension and is created after you make file selections and configure backup settings.
to kill yall so just leave this question alone
What is the file extension What is the file extension
file extension for video is 101
.html, .php, or .htm
Go take the test and see if you can file for an extension