1/ When castling, although two men are moved, it only counts as
2/ When playing on RedHotPawn, you just make the King's move,
the machine will automatically move the Rook as well.
3/ When playing on a normal board, the King must be moved first,
then the Rook.
4/ Whichever side you castle the King only moves two squares.This
means that on the King's side the king lands on g1, and on the
queen's side on c1. (Please note that both Bad wolf and are
Korinthenkacker are not correct when they say the king moves 3
squares). In either case the Rook moves to the square the other
side of the King, (f1 on the King's side, di on the Queen's side).
5/ All the squares between the King and the rook on the side you
want to castle must be empty.
6/ You cannot castle if either the square the King would pass or the
square it would land on is attacked by one of your opponents
men. (It does not matter if at that time the rook is attacked, or
on the queen's side if b1 is attacked).
7/ The King and the rook you want to castle with must not have
moved. (If you have moved either man and have moved it back
to it's original square you cannot castle).
8/ You cannot castle if you are in check, but if you did not move the
king to get out of check, you can still castle after being in check,
provided all the other rules are met.