A pin ties an enemy piece to a more valuable piece behind it, freezing it in place. In an absolute pin, that piece is pinned directly to the king, so it literally cannot move — doing so would be illegal. Our bishop on b5 already pins the knight on c6 to the king on e8: the knight is stuck. The winning technique is simple and powerful — once a piece is pinned and can't run, pile more attackers onto it. Play d4 to prepare d5, adding a second attacker to the frozen knight.Play pawn to d4.