1. En Passant
When a pawn advances two squares and there is an opponent's pawn on an adjacent file next to its destination square, then the opponent's pawn can capture it en passant, and move to the square the pawn passed over. However, this can only be done on the very next move, or the right to do so is lost.
2. Pawn promotion
On reaching the last rank, a pawn must immediately be exchanged, as part of the same move, for [either] a queen, a rook, a bishop, or a knight, of the same colour as the pawn, at the player's choice and without taking into account the other pieces still remaining on the chessboard. The effect of the promoted piece is immediate and permanent!
Castling consists of moving the king two squares along the first rank toward a rook (which is on the player's first rank.) and then placing the rook to the last square the king has just crossed.