🏰 Castling and king safety

The king is the piece you can't lose, and in the center it's exposed to everything. Castling is the special move that solves it: you move king and rook at once, hide the king in a corner and activate the rook. It's almost always the most important move of the opening.

There are two: kingside castling (toward the king's flank, quicker and safer) and queenside castling (toward the queen's flank, more aggressive, but it leaves the a-pawn a bit loose). Requirements: king and rook haven't moved, no pieces in between, and the king isn't in check nor passes through an attacked square.

Once castled, mind the shield: don't push the pawns in front of your king without reason, because each advance opens cracks. And remember to make “luft” (a little gap with h3 or g3) so your king doesn't fall to a back-rank mate.