pop-global-mark-command, you can quickly jump back to the
locations you were before, like tracking back your bread crumbs.
A typical example of this is when doing some programming and looking up some function in another file, which refers to a function in yet another file, and so on – for example, see navigating through source code using tags.
C-x C-SPC (the default key binding for
pop-global-mark) to make your
journey back to where you came from; it works in a cyclical fashion as well,
so you can go on and on.
Quite useful – you may want to use a more convenient key binding though. Admittedly, it's hard to come up with any intuitive keybinding which is not already taken by something else…