Editable software

How awesome is it that if some functionality doesn't exist in [[Emacs]], you can just add it in with your own function. (And usually you don't have to write it yourself - a quick search will find that someone else has done it already.)

e.g., I wanted a way to remove a link in org-mode, but leave the description. (Kind of surprised that isn't built-in to be honest, but there we go). The Emacs StackExchange has a bunch of ways of doing that.