The tldr project is a collection of community-maintained help pages for command-line tools, that aims to be a simpler, more approachable complement to traditional man pages.

Run it by typing "tldr <command>" into terminal.

Maybe you are new to the command-line world? Or just a little rusty? Or perhaps you can't always remember the arguments to lsof, or tar?

It also is more digestable than man pages which blasts pages of useless stuff at you every time you use it.
