Game analysis
Blunder
A blunder is a serious mistake that substantially worsens a position’s prospects. It may lose a piece, overlook mate or throw away a win. Which moves an analysis platform labels as blunders depends on its evaluation model and the position.
A practical example
You move a defender away and miss that the opponent now has mate in one. Another example is leaving a rook undefended without sufficient compensation.
A common mistake
Focusing only on a red error marker or directly comparing labels from different platforms. For training, the useful question is which opposing threat you missed and how to recognize it next time.
Try this in your next review
Return to the position before the mistake. Name the enemy threat and find at least one safe candidate move. Then use analysis to verify that your alternative actually prevents the critical danger.