What the heck is an autocancel?! (SSBM)

Correction: Normal landing lag for most characters is 4 frames, not 3, for all characters except Pichu, Ganon, DK and Bowser. This is a guide explaining what an autocancel is and how to explore using them for your character as well. It's intended for newer players who have been told to practice their SHFFL'd aerials and who may not realize that they have more options to leverage their aerials with.