A while ago, I learned something new about the ‘cd’ command:
This changes directory back to the previous directory you were in. You can do it again to move back and forth. Quite useful! a bit like a simpler pushd/popd/dirs.
It’s not documented in bash online help, manpage or info doc as far as I can see. I guess it’s an old feature inherited from the Bourne shell; other Bourne-compatible shells have this feature too, even C shell has it.