In tennis, an official is a person who ensures that a match or tournament is conducted according to the International Tennis Federation Rules of Tennis and other competition regulations.

At the highest levels of the sport, a team of up to eleven officials may be on court at any given time. These officials are broken up into categories based on their responsibility during the match. Contrastingly, many tennis matches are conducted with no officials present directly on court.

Tennis officials are certified by their respective national association. The ITF also certifies officials in the categories of chair umpire, referee and chief umpire. Each ITF certification or "badge" is broken into four certification levels. The first, white badge, is considered sufficient for officiating at the highest levels of tennis within the official's own nation and is not divided into categories. The following three, bronze (chair umpire only), silver, and gold badge, are considered international certifications. These international officials are those seen at the highest levels of play like the Grand Slams, ATP and WTA Tours, and the Fed and Davis Cups.

An official is someone who holds an office (function or mandate, regardless whether it carries an actual working space with it) in an organization or government and participates in the exercise of authority (either his own or that of his superior and/or employer, public or legally private).

A government official or functionary is an official who is involved in public administration or government, through either election, appointment, selection, or employment. A bureaucrat is a member of the bureaucracy. An elected official is a person who is an official by virtue of an election. Officials may also be appointed ex officio (by virtue of another office, often in a specified capacity, such as presiding, advisory, secretary). Some official positions may be inherited.

A person who currently holds an office is referred to as an incumbent.

The word official as a noun has been recorded since the Middle English period, first seen in 1314.^{[citation needed]} It comes from the Old French official (12th century), from the Latin officialis ("attendant to a magistrate, public official"), the noun use of the original adjective officialis ("of or belonging to duty, service, or office") from officium ("office"). The meaning "person in charge of some public work or duty" was first recorded in 1555. The adjective is first attested in English in 1533, via the Old French oficial.

Tennis is a sport usually played between two players (singles) or between two teams of two players each (doubles). Each player uses a racket that is strung to strike a hollow rubber ball covered with felt over a net into the opponent's court. Object of the game is to play the ball in such a way that the opponent is not able to play a good return. Tennis is an Olympic sport and is played at all levels of society at all ages. The sport can be played by anyone who can hold a racket, including people in wheelchairs.

The modern game of tennis originated in Birmingham, England in the late 19th century as "lawn tennis" which has close connections to various field/lawn games as well as to the ancient game of real tennis. Up to then, "tennis" referred to the latter sport: for example, in Disraeli's novel Sybil (1845), Lord Eugene De Vere announces that he will "go down to Hampton Court and play tennis. As it is the Derby [classic horse race], nobody will be there". After its creation, lawn tennis spread throughout the upper-class English-speaking population before spreading around the world.