Waiting move
A waiting move keeps your position exactly as strong as before and simply hands the opponent the obligation to move, which helps whenever every reply they have makes their position worse.
Chess has no pass, so when the position you want is the one where the opponent is to move, you need a move that changes nothing that matters. That is the whole job of a waiting move.
Good candidates keep every important square covered: a rook sliding along a line it already controls, a king stepping between two equally good squares, or a pawn push held in reserve for exactly this moment. A move that loosens your grip, even slightly, is not a waiting move at all.
The example shows the idea in its simplest form. With White to move there is no mate, but Rd1 keeps Black's king confined and leaves it a single legal reply, Kb8, after which Rd8 is mate. The rook could equally go to e1, f1, g1 or h1. Rc1 would not do, because after Kb8 the check on c8 lets the king capture the rook.
Two warnings apply. First, make sure the opponent still has a legal move after your waiting move, or you have stalemated them. Second, check that the opponent cannot use the extra move for a counter-threat of their own. Waiting moves are strongest in endings, where the side to move often has nothing useful to do.
Also worth reading is King and rook checkmate. King and rook checkmate is the basic ending in which a king and rook force mate against a lone king, by pushing it to an edge with the help of the opposition.
A neighboring idea is Mutual zugzwang. A mutual zugzwang is a position in which whichever player has to move is worse off, so each side would gladly pass, and the result depends entirely on whose turn it is.
Endgame ideas like "Waiting move" are won or lost on small details, which a coach can check in your own games. The first lesson with George Li is where that review starts.
Related terms
A tempo is a single move counted as a measure of time: gaining one means making a useful move that also forces the opponent to react, while losing one means spending a move that accomplishes nothing.
Zugzwang is the bind of having to move when standing still would be best: the player on move has only moves that weaken the position, and since passing is not allowed, the duty to move itself costs something.
A mutual zugzwang is a position in which whichever player has to move is worse off, so each side would gladly pass, and the result depends entirely on whose turn it is.
A quiet move is a move that makes no capture and gives no check, yet creates a decisive threat or removes the opponent's last defense, so it is easy to overlook among more forcing moves.
King and rook checkmate is the basic ending in which a king and rook force mate against a lone king, by pushing it to an edge with the help of the opposition.
A reserve tempo is a spare, harmless move, usually a pawn move, that one side can make without damaging its position, passing the obligation to move across to the opponent.
Guides that go further
What to decide first, the questions to ask, what a first lesson should show and the red flags to avoid.
How much does chess coaching cost?
Published rates for private, group and subscription chess coaching, with the source and the date of each.
A game review, a read on your level and a written study plan from George Li.
Want to spot this in your own games?
A first lesson starts with your games: George reviews them and builds a study plan around what he finds.