Pillaring
Pillaring is a tactic in Super Smash Bros. Melee of pressuring an opponent's shield using SHFFL'd aerials and shines, used by Fox and Falco. This technique is commonly used in high-level play. Pillaring is sometimes viewed as general shield pressure. It is also commonly mistaken for Falco's vertical down aerial and shine combos.
How to perform
Against a shielding opponent, the easiest way to pillar is to SHFFL a down aerial and immediately shine. The shine is then jump-canceled into another SHFFL'd down aerial, and the cycle continues. However, other aerials may be used, depending on preference. This can be mixed up with multishines and waveshines. Jabs, down tilts (for Falco) and jump-canceled grabs out of shine are also popular mix-ups.
Uses
Pillaring can pressure an opponent in a shield, forcing them to roll out of it, which can be chased. It is possible for Falco's down aerial pillar to be shield-grabbed, but it requires very good timing. If the opponent is not good at defending against pillaring, their shield may be broken. This is rare in high-level play.
Technicalities
Pillaring can be shield grabbed or broken out of by out of shield options such as Samus's Screw Attack, Bowser's Whirling Fortress, Fox's shine or neutral aerial, and a few other moves. The exact timing of when to break out of the pillar depends on how the opponent times his aerials and the breakout attack used.