ugh. i was jumping between a deep project folder and /var/log over and over, typing teh full paths each time. then I learned cd -. It takes you back to the previous directory, and running it again takes you back again. It toggles between two places.
then i found pushd and popd. pushd /some/dir changes directory and remembers where you were on a stack. popd goes back. dirs -v shows teh stack. Works in bash and zsh, and PowerShell 6.2+ supports cd - too. any ideas??