Dance is a type of art that generally involves movement of the body, often rhythmic and to music. It is performed in many cultures as a form of emotional expression, social interaction, or exercise, in a spiritual or performance setting, and is sometimes used to express ideas or tell a story. Dance may also be regarded as a form of nonverbal communication between humans or other animals, as in bee dances and behaviour patterns such as a mating dances. Definitions of what constitutes dance can depend on social and cultural norms and aesthetic, artistic and moral sensibilities. Definitions may range from functional movement (such as folk dance) to virtuoso techniques such as ballet. Martial arts kata are often compared to dances, and sports such as gymnastics, figure skating and synchronized swimming are generally thought to incorporate dance. In some cases, the motion of ordinarily inanimate objects may be described as dance (the leaves danced in the wind). There are many styles and genres of dance. African dance is interpretative. Ballet, ballroom and tango are classical dance styles. Square dance and electric slide are forms of step dance, and breakdancing is a type of street dance. Dance can be participatory, social, or performed for an audience. It can also be ceremonial, competitive or erotic. Dance movements may be without significance in themselves, as in ballet or European folk dance, or have a gestural vocabulary or symbolic meaning as in some Asian dances. Choreography is the art of creating dances. The person who creates (i.e., choreographs) a dance is known as the choreographer. In dance, choreography is the act of designing dance. Choreography may also refer to the design itself, which is sometimes expressed by means of dance notation. A choreographer is one who designs dances. Dance choreography is sometimes called dance composition. Aspects of dance choreography include the compositional use of organic unity, rhythmic or non-rh thmic articulation, theme and variation, and repetition. The choreograhic process may employ improvisation for the purpose of developing innovative movement ideas. In general, choreography is used to design dances that are intended to be performed as concert dance. The art of choreography involves the specification of human movement and form in terms of space, shape, time and energy, typically within an emotional or non-literal context. Movement language is taken from the dance techniques of ballet, contemporary dance, jazz dance, hip hop dance, folk dance, religious dance, pedestrian movement, or combinations of these. Dances are designed by applying one or both of these fundamental choreographic methods: Improvisation, in which a choreographer provides dancers with a score (i.e., generalized directives) that serves as guidelines for improvised movement and form. For example, a score might direct one dancer to withdraw from another dancer, who in turn is directed to avoid the withdrawal, or it might specify a sequence of movements that are to be executed in an improvised manner over the course of a musical phrase, as in contra dance choreography. Improvisational scores typically offer wide latitude for personal interpretation by the dancer. Planned choreography, in which a choreographer dictates motion and form in detail, leaving little or no opportunity for the dancer to exercise personal interpretation. Several underlying techniques are commonly used in choreography for two or more dancers: Mirroring - facing each other and doing the same Retrograde - performing a sequence of moves in reverse order Canon - people performing the same move one after the other Levels - people higher and lower in a dance Shadowing - standing one behind the other and performing the same moves Unison - two or more people doing a range of moves at the same time Movements may be characterized by dynamics, such as fast, slow, hard, soft, long, and short.