Protected Passed Pawn is a passed pawn defended by a friendly pawn, and this support makes it much more dangerous.

Why Is It Valuable?

• It forces the opponent's pieces into passive defense.
• It has a better chance of advancing even without king support.
• It often creates a constant calculation burden for the opponent.

This structure, especially praised by Nimzowitsch, is one of the most reliable winning tools in the endgame.