How to loop through all but the last item of a list?

I would like to loop through a list checking each item against the one following it.

Is there a way I can loop through all but the last item using for x in y? I would prefer to do it without using indexes if I can.

Note

freespace answered my actual question, which is why I accepted the answer, but SilentGhost answered the question I should have asked.

Apologies for the confusion.