In chess, a tactic is a sequence of moves that each makes one or more immediate threats – a check, a material threat, a checkmating sequence threat, or the threat of another tactic or otherwise forcing moves – that culminates in the opponent's being unable to respond to all of the threats without making some kind of concession. Most often, the immediate benefit takes the form of a material advantage or mating attack; however, some tactics are used for defensive purposes and can salvage material that would otherwise be lost, or to induce stalemate in an otherwise lost position.

Tactics are usually contrasted with strategy, whereby the individual moves by themselves do not make indefensible threats, and the cumulative advantage of them takes longer to capitalise. The dichotomy can be summarised as tactics concerning short-term play and strategy concerning long-term play. Examples of strategic advantages are weaknesses in, compromised pawn structure in, and sustained pressure on, the opponent's position. Often, to dichotomize strategy and tactics, sequences of moves that make strategic instead of tactical threats or use tactical threats to obtain a strategic advantage are also classified as tactics.

Tactics usually follow one of a number of repeating patterns; these include forks, skewers, batteries, discovered attacks, undermining, overloading, deflection, pins, and interference. The Encyclopedia of Chess Middlegames gives the following tactics categories: Annihilation of Defense, Blockade, Decoying, Deflection, Demolition of Pawns, Discovered Attack, Double Attack, Interception, Intermediate Move, Overloading, Passed Pawn, Pawns Breakthrough, Pin, Pursuit (perpetual attack), Space Clearance, Trapping a piece, and X-ray Attack. Often tactics of more than one type are conjoined in a combination.

A piece is said to attack (or threaten) an opponent's piece if, on the next move, it could capture that piece. A piece is said to defend (or protect) a piece of the defender's color if, in case the defended piece were taken by the opponent, the defender could immediately recapture. Attacking a piece usually, but not always (see Sacrifice), forces the opponent to respond if the attacked piece is undefended, or if the attacking piece is of lower value than the one attacked.

When the piece attacked is a king, then a player has at most three options:

When the attacked piece is not a king, a player may have additional options, beyond the ones listed above:

When a player is able to capture the opponent's piece(s) without losing any of their own (or losing a piece of lesser value), the player is said to have "won material"; i.e., the opponent will have fewer (or less valuable) pieces remaining on the board. The goal of each basic tactic is to win material. At the professional level, often the mere threat of material loss (i.e., an anticipated tactic) induces the opponent to pursue an alternative line. In amateur games, however, tactics often come to full fruition – unforeseen by the opponent and resulting in material gain and a corresponding, perhaps decisive, advantage. Material gain can be achieved by several different types of tactics.

A discovered attack is a move that allows an attack by another piece. A piece is moved away so as to allow the attack of a friendly bishop, rook or queen on an enemy piece. If the attacked piece is the king, the situation is referred to as a discovered check. Discovered attacks are powerful since the moved piece may be able to pose a second threat.