what is a blunder in chess

In chess, a blunder is a critically bad move or decision that severely worsens the players situation by allowing a loss of material, checkmate, or anything similar. It is usually caused by some tactical oversight, whether due to time trouble, overconfidence, or carelessness. Blunders are subjective, and what qualifies as a "blunder" rather than a normal mistake depends on the level of the player. Weak moves from novice players might be explained by the player's lack of skill, while the same move from a master might be called a blunder. Blunders are typically marked with a double question mark ("??") after the move in chess annotation. Blunders are important because they can cause a player to lose material or be checkmated, but they can also lead to a strategically lost position. Failing to take advantage of an opponent's mistake is also sometimes described as a blunder.