The Parry is a sword technique from The Legend of Zelda: The Wind Waker. It is taught to Link by Orca on Outset Island near the start of the game, and is one of the most useful techniques that Link learns during his quest; it is necessary to finish the game, as the final strike during the last battle requires the Parry. It is activated by L-targeting an enemy and pressing the A button just before they attack, at which time the A button in the heads up display will flash, Link's sword will flash green, and a sound will be heard.
There are two common variations of this technique, and one only done in rare circumstances; one for evading vertical strikes, which results in a sidelong roll and counter behind the enemy and one for evading horizontal strikes, which has Link jumping over the enemy and striking its head. It is useful when removing the armor and helmets of Darknuts. The uncommon one is performed on a few select enemies, such as a Magtail or Floormaster when it is grabbing Link. It is a jump straight up, followed by slamming the edge of the blade down on the enemy. Link performs a combination of the two common variations when performing the final strike on Ganondorf.
Two Hidden Skills in The Legend of Zelda: Twilight Princess, the Back Slice and the Helm Splitter, act the same way as the main variations of the parry, but are activated differently and are also learned separately. Also, the Ending Blow is a somewhat similar motion to the third, less common parry.
The technique's name is somewhat of a misnomer, as Link actually never parries the enemy's blow, but instead dodges and counterattacks it.