<p>My general consensus on it is that the professors REALLY don’t care if you show up, but just don’t expect them to give a crap about your grade if you never came to class either. Especially in large classes, unless there’s some kind of roll-taking, professors generally continue on with whatever they had planned even if few people show up (they just might give a pop quiz for extra credit consisting of “Write you name and your favorite color on a sheet of paper and hand it in for 10 extra points on your next exam”). Several of my smaller classes have had stringent attendance policies, but often my large lecture classes did not. The few big classes that did had something along the lines of a sign-in sheet on the wall, or GTA’s checking a seating chart.</p>