In tennis, a let is a situation where players replay an entire point, and it can be called for a few reasons, during a serve (a service let) or during a rally. The most common instance of a let is a service let, which occurs when the ball clips the net tape but still lands in the service box. This causes a hindrance for the opponent, and the serve is retaken. A let can also be called if a point is disturbed by external intervention, such as the arrival of a ball from a nearby court. A let is not considered a fault, and the server may repeat the service attempt). The term "let" is thought to have originated from the Saxon word "lettian," which referred to a hindrance. The call of a let is an important part of the game and can actually turn a match on its head, as a player will be forced to reset their mind to replay a point that they may have been in prime position to win. In professional-level tennis, an umpire is the one who calls "let," while in a casual match-up, the players can either designate a third party or agree that both players should agree on a call.