What is Castling in a Chess Game

Video Transcript

"Castling is another thing that you do need to know about in chess and indeed it is very important to know it and it does occur in almost every game and castling is basically moving the king in one move and this is done in one move, the king is moved in two squares and the rook is also moved two squares. That represents one move and that is castling. Castling can be done either on the king's side as I just demonstrated. It can also be done on the queen's side although it is done less often on that side. Queen's side castling again the king moves two squares and the rook in this instance moves three squares. That is an example of queen's side castling. The thing where people get confused is that they tend to, with queen's side castling, remember the king starts one square further away, they tend to move the king to here, that is incorrect, the king always is in all castling moves two squares. In this instance the rook does move the three squares. There are certain rules about when and where you cannot castle and basically they are these. You cannot castle if you are in check so let's put a black queen there, the white king is in check and he cannot castle. Similarly you cannot castle into check so let's have the white queen here this time and again white cannot castle because he would be castling into check. You also cannot castle through check. Castling through check would be this because the white king actually crossed the square controlled by the black queen where he would have been checked and therefore he cannot play, he cannot castle. The other move, the other requirements are that the king must not have been moved prior to castling. If you have moved and you come back to the square it is no good, you can't castle nor can you castle if you have for any reason moved this castle, this rook, even if you've gone back to that square but of course you could do this and let me quickly summate with this. If you had this situation and for whatever reason you had moved this rook at some point but you have not moved your king and you are not breaking any of the other rules, you could still castle on the queen's side."