The fine print of the two special moves, practised on the board. When you may castle and when you may not, which side to castle on, and what to do in check. And the one moment when en passant is allowed. This is a basics course with 2 lessons and 7 interactive exercises, suited to players rated around 400 (complete beginners). Every exercise is played on a real board with feedback after each move, there is nothing to install, and it is free.