Discovered attack
In a discovered attack one of your pieces steps off a line, and that move unmasks a bishop, rook or queen standing behind it, so a single turn produces two threats.
Two of your pieces work as a team here: a mover in front and a long-range piece behind it on the same line. While the mover stays put, the line is shut. When it jumps away, the line opens and the piece behind suddenly hits an enemy target.
The best part is that the mover keeps its own freedom. It can capture, give check, or attack something, and the opponent must handle both its threat and the uncovered one with a single reply. That is why discovered attacks so often win a whole piece or more.
Some versions are quiet and some are forcing. If the uncovered target is the king, you have the stronger discovered check. If the mover lands with an attack on the queen, even a well-defended target may not matter, because the queen cannot do two jobs at once.
To find the pattern, look for your own bishop, rook or queen with a friendly piece on its line toward an enemy target, then ask what that friendly piece could capture or attack if it left. To guard against it, notice when your valuable pieces face a line where an enemy piece stands in front of its own long-range piece.
In the diagram White plays Bxd6. The bishop captures the rook and leaves the e-file, so the rook on e1 now attacks the queen on e8. If Black plays Qxe1+ and Kxe1, White has won a queen and a rook for a rook.
Also worth reading is Pin. A pin ties a piece to its square: a bishop, rook or queen attacks it, and stepping aside would expose a more valuable piece standing behind it on the same line.
A neighboring idea is Windmill. A windmill is a repeating pattern in which a rook moves away to give a discovered check, captures a piece, returns with check, and repeats, winning another enemy piece with each swing.
A neighboring idea is X-ray attack. An x-ray is hidden pressure: a bishop, rook or queen bears on a piece or square beyond an enemy piece in its way, and the pressure turns real once the blocker moves or is exchanged.
Knowing "Discovered attack" helps most once you can spot it in a real game. A first lesson with George Li starts from your own games and finds the tactics you keep missing.
Related terms
A discovered check is a check from a piece that did not move: a bishop, rook or queen is unmasked when the piece in front of it leaves the line to the king.
A double check is a single move that puts the enemy king under attack from two pieces simultaneously, typically one that moved and one it unmasked, so only a king move can answer it.
A double attack is one move that creates two threats at once, whether they come from a single piece or from two, and whether they aim at pieces or at checkmate.
A fork is a move that leaves one of your pieces threatening two enemy pieces together. Because the opponent gets only one turn to respond, something usually falls.
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.