Ballet (French: [balɛ]) is a type of performance dance that originated during the Italian Renaissance in the fifteenth century and later developed into a concert dance form in France and Russia. It has since become a widespread and highly technical form of dance with its own vocabulary. Ballet has been influential globally and has defined the foundational techniques which are used in many other dance genres and cultures. Various schools around the world have incorporated their own cultures. As a result, ballet has evolved in distinct ways.

A ballet as a unified work comprises the choreography and music for a ballet production. Ballets are choreographed and performed by trained ballet dancers. Traditional classical ballets are usually performed with classical music accompaniment and use elaborate costumes and staging, whereas modern ballets are often performed in simple costumes and without elaborate sets or scenery.

Ballet is a French word which had its origin in Italian balletto, a diminutive of ballo (dance) which comes from Latin ballo, ballare, meaning "to dance", which in turn comes from the Greek "βαλλίζω" (ballizo), "to dance, to jump about". The word came into English usage from the French around 1630.

In French, the word refers to a ballet performance, a ballet work, and possibly to the dance genre itself, although the expression danse classique also exists for the latter meaning, is less equivocal and is more commonly used when referring to the learning of this dance.^{[citation needed]}

Ballet originated in the Italian Renaissance courts of the fifteenth and sixteenth centuries. Under Catherine de' Medici's influence as Queen, it spread to France, where it developed even further. The dancers in these early court ballets were mostly noble amateurs. Ornamented costumes were meant to impress viewers, but they restricted performers' freedom of movement.

The ballets were performed in large chambers with viewers on three sides. The implementation of the proscenium arch from 1618 on distanced performers from audience members, who could then better view and appreciate the technical feats of the professional dancers in the productions.

French court ballet reached its height under the reign of King Louis XIV. Louis founded the Académie Royale de Danse (Royal Dance Academy) in 1661 to establish standards and certify dance instructors. In 1672, Louis XIV made Jean-Baptiste Lully the director of the Académie Royale de Musique (Paris Opera) from which the first professional ballet company, the Paris Opera Ballet, arose. Pierre Beauchamp served as Lully's ballet-master. Together their partnership would drastically influence the development of ballet, as evidenced by the credit given to them for the creation of the five major positions of the feet. By 1681, the first "ballerinas" took the stage following years of training at the Académie.

Ballet started to decline in France after 1830, but it continued to develop in Denmark, Italy, and Russia. The arrival in Europe of the Ballets Russes led by Sergei Diaghilev on the eve of the First World War revived interest in the ballet and started the modern era.