Castling:- Castling is a process of creating a castle basically for protection from enemies and to avoid check. This process requires the King, a Rook and some Pawns (if kingside castling is done, then 3 pawns are necessary and if queenside castling is done, 4 pawns are required). The structure for a castle is like this:-
♟ ♟ ♟ (kingside castling)
🛢 👑
or like this
♟ ♟ ♟ ♟
👑 🛢 (queenside castling)
There are several rules for castling, they are:-
1) If a team does castling, then the other team can castle on the other side. If white team does kingside, black can do only queenside.
2) Castling cannot be done if there is any other piece between the King and the Rook which will castle. Pieces between themmust be moved to castle.
3) Castling cannot be done if the King or the square where it will move is under check.
4) Castling cannot be done if the Rook or the King is moved from their original positions to other squares.
5) Each team can castle only one time. If their castle gets destroyed by enemies, no new castle could be formed.
In this example, king is gonna move kingside 2 steps to castle
En Passant:- The En Passant rule is a special Pawn capturing move in chess. "En passant" is a French expression that translates to "in passing", which is precisely how this capture works. Pawns can usually capture only pieces that are directly and diagonally in front of them on an adjacent file. In this example, white Pawn will move to d6 square to pass in and capture the square.
Stalemate:- Stalemate is a situation in chess where the player whose turn it is to move is not in check and has no legal move. Stalemate results in a draw. During the endgame, stalemate is a resource that can enable the player with the inferior position to draw the game rather than lose.