Push your present working directory to a stack that you can pop later
pushd /tmp
If are a Bash user and you are in a directory and need to go else where for a while but don't want to lose where you were, use pushd instead of cd.
cd /home/complicated/path/.I/dont/want/to/forget
pushd /tmp
cd thing/in/tmp
popd (returns you to /home/complicated/path/.I/dont/want/to/forget)
alias +='pushd'
alias -- -='popd'
alias +='pushd'
alias -- -='popd'
alias ?='dirs -v'