Strategy & opening play
Tempo
A tempo is a unit of time in chess, usually one move. Developing with a threat can gain a tempo because the opponent must respond. The term also matters in endgames, where one extra or saved move can decide the result.
A practical example
Your knight develops while attacking the enemy queen. If the queen must move to a less active square, you have improved your development while the opponent has moved the same piece again.
A common mistake
Counting every queen attack as a gained tempo. If the queen reaches a better square with a stronger threat, the attempted attack may cost time. Repeated knight moves can also delay your own development.
Try this in your next review
After a sequence, compare which side actually improved its position. In pawn endings, count concrete king moves and check who will have the move at the critical moment.