By pressing Z, L, or R slightly before landing on the ground, a player can reduce their recovery time, a significant decrease that greatly increases a character's maximum rate of attack. L-canceling is no longer available in Brawl, though auto-cancel is in.
To L-cancel, press L, R, or Z (only Z and R work in SSB) within 6 frames of landing on the ground while the character is still performing an aerial attack. If performed correctly, the character's recovery animation will be played at twice its normal speed in SSBM, effectively cutting recovery time in half. If the number of frames of the lag divided by two ends with a decimal (i.e. 15/2 = 7.5), it will be rounded downwards. In SSB, however, the recovery animation is erased completely, allowing one to move immediately after any aerial attack. L-canceling can only be used with aerial attacks involving the A button; it is impossible to L-cancel a special move. It is also impossible to L-cancel Mr. Game & Watch's neutral aerial and up aerial attack.
Auto-canceling occurs when the character lands at the earliest or last frames of an aerial attack. This causes the character to land with normal landing lag (usually 4 frames) without any additional lag from using the attack. When an attack is auto-canceled, L-canceling has no effect.
If one is hit while being airborne, and they press Z, L or R as soon as they hit the ground, this technique can be called landrolling. This technique is common is SSB, for in Peach's Castle, there is a bumper at the top, and if one gets hit, they can press Z, L or R as soon as they land, and then they roll.