How to change or remove file extensions in Windows

Say you have a bunch of files and you want to quickly change or remove the file extension of all of them. Turns out that's very simple to do with the command-line in Windows. I had no idea...

Change

This will change all files with old file extension to have the new file extension:

ren *.old *.new

Remove

This will remove the old file extension:

ren *.old *.

Simple!