A Fast fall is the act of falling more quickly than usual in mid-air. It is performed by tapping down on the control stick while falling, as long as the character is not tumbling. The character will continue to fast fall until landing on the platform or taking a hit. Gravity is ignored once a fast fall is begun; the character's downward velocity is simply set to their fast falling speed without accelerating. Fast falling is a technique commonly used to speed up a character's game, especially after a short hop. It is a part of SHFFLing, an advanced technique.
Stall-then-fall aerials have an effect similar to fast falling, though the move is an attack, and most of the time cannot be stopped or slowed.
If the player taps down on the control stick while hanging from a ledge, their character will begin to fast fall right after letting go of it, whereas if simply tilted down or in the opposite direction of the ledge, they will merely let go of it. This also works with down specials, except for ones that slow down falling or gain height, such as Fox's Reflector or Luigi's Luigi Cyclone.
In Super Smash Bros. and Super Smash Bros. 4, the character will flash and a white star will appear at his or her torso when fast falling (in Smash 4, the stars can appear in several places, but all are still located near the fast-falling character's midsection). In Super Smash Bros. Melee, a "whoosh" sound will be heard when fast falling, but there is no visual indicator, making it harder to pick up on, especially with other surrounding sound effects. There is no indicator in Super Smash Bros. Brawl whatsoever. In Super Smash Bros. Ultimate, fast falling is indicated by a small flashing blue-purplish star appearing next to the character for a brief moment, similar to Smash 4.
In Smash 4 and Ultimate, characters can cancel a fast fall by using an aerial attack. This will set their falling speed to the normal maximum.
Falling speeds for DLC characters are not known at this time.