What is a fault in tennis?

The server has two serves for each point. A first-serve fault gives them a second serve. A second fault in a row is a double fault, and the receiver wins the point.

A serve that touches the net and then lands in the correct box is not a fault but a let, and is replayed.

Questions

What counts as a fault?

A serve landing outside the correct box, in the net, a foot fault, or swinging at the toss and missing.

What happens after a fault?

On a first serve you get a second serve. After a second fault you lose the point.

Sources

  • ITF Rules of Tennis