Auto-canceling, also known as smooth landing, auto L-cancelling and aerial lag redution, is the act of landing during the beginning or ending frames of an aerial attack and shortening the ending lag of the move. Auto-canceling an attack sometimes produces less landing lag than a regular landing, while landing during the middle of an aerial attack almost always results in a significant delay.
Most aerial attacks can be auto-cancelled both during the first few frames or the last few frames, though some cannot be auto-cancelled at the start, at the end, or even both; every character has a specific auto-canceling window. Auto-canceling can be used in canceling the ending lag of using the Dimensional Cape or using Quick Attack into the ground to perform Quick Attack canceling.
Short hop fast fall L-cancel, commonly abbreviated as "SHFFL" (pronounced like the word "shuffle"), is a combination of three advanced techniques that, for most characters, results in the quickest ways to perform aerial attacks and be able to follow up with more attacks. A SHFFL, per its name, comprises short hopping, fast falling and auto-cancelling, allowing the player to act even sooner than a normal auto-cancel, improving combos and the neutral game of a player.