Banish is an action of putting a card from the field into its owner's Graveyard, other than by Destroy.
Unlike Destroy that applies to both players, a player can only banish a card he/she controls. You can't banish a card that is controlled by your opponent.
Usually, banish is used for a cost to activate abilities or as an additional cost to play cards.
Banish can also become an indirect removal via "forced banish". It's called indirect removal because the spells and abilities that caused the Banish act usually targets the player, not the card. Mostly, this type of "force banish" effects found in Darkness attribute cards.
- The term "Banish" in this game is actually identical to "Sacrifice" in other trading card games such as Magic: The Gathering or Yu-Gi-Oh!.