TRAMP is the Emacs feature that lets you edit files on other servers or as other users transparently. It's super convenient when you can't be arsed to drag the configuration all the way over there, or if Emacs isn't installed.
But I only need to every once in a while so I always forget the exact syntax even thought it isn't very diffcult.
Today I thought I had forgot it again, but instead I had been too clever with a socks configuration which prevented me to connect to otheraccount@localhost... Duh.
Anyway, when opening a file, just enter this:
and hit Tab to get file completion in the other account home dir.
 Yes, I know of -u to load