Capture
When a piece lands on a square that is occupied by one of the opponent’s pieces, the opponent’s piece is captured. It is removed from the board and given to the player who captured it, and it is considered to be “in hand.”

Drop
When a player has pieces in hand, he can choose to replay that piece on the board instead of moving one of his pieces. Except for a limited number of illegal drops, a piece can be dropped anywhere on the board – including inside the opponent’s camp and to deliver checkmate. Pieces must always be dropped in their unpromoted state.

Illegal Drops
There are three kinds of illegal drops.

• A piece must be able to legally move when dropped. This means that a Pawn and Lance cannot be dropped on the last rank, and a knight cannot be dropped on the last two ranks. Dropping Pawns and Lances behind pieces that block them is allowed.All of these are illegal drops, because they will never be able to move.
• A player may not have two pawns in the same file. The only exception is when one of the pawns is Promoted.
  Dropping the pawn on the second file from the right is an illegal move because there is already a pawn. However, dropping a pawn on the third file is legal because the pawn is promoted.
• A player may not deliver checkmate with a dropped pawn. This means that immediately after the drop, in the same move, the dropped pawn will deliver a checkmate.
  
  Dropping the pawn in front of the king is an illegal move because it is checkmate.

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