When play is structured and goal orientated it is often presented as a game. Play can also be seen as the activity of rehearsing life events e.g. young animals play fighting. These and other concepts or rhetorics of play are discussed at length by Brian Sutton-Smith in the book The Ambiguity of Play. Sometimes play is dangerous, such as in extreme sports. This type of play could be considered stunt play, whether engaging in play frighting, sky-diving, or riding a device at high speed in an unusual manner.

Definitions

The seminal text in play studies is Homo Ludens by Johan Huizinga. Huizinga defined play as follows:

quote: Summing up the formal characteristic of play, we might call it a free activity standing quite consciously outside ‘ordinary' life as being ‘not serious' but at the same time absorbing the player intensely and utterly. It is an activity connected with no material interest, and no profit can be gained by it. It proceeds within its own proper boundaries of time and space according to fixed rules and in an orderly manner. It promotes the formation of social groupings that tend to surround themselves with secrecy and to stress the difference from the common world by disguise or other means.

This definition of play as constituting a separate and independent sphere of human activity is sometimes referred to as the "magic circle" notion of play, and attributed to Huizinga, who does make reference to the term at some points in Homo Ludens. According to Huizinga, within play spaces, human behavior is structured by very different rules: e.g. kicking (and only kicking) a ball in one direction or another, using physical force to impede another player (in a way which might be illegal outside the context of the game).

Another classic in play theory is Man, Play and Games by Roger Caillois. Caillois borrows much of his definition from Huizinga. Caillois coined several formal sub-categories of play, such as alea (games of chance) and ilinx (vertigo or thrill-seeking play).

According to Stephen Nachmanovitch, play is the root and foundation of creativity in the arts and sciences as well as in daily life.

quote: Improvisation, composition, writing, painting, theater, invention, all creative acts are forms of play, the starting place of creativity in the human growth cycle, and one of the great primal life functions.

A notable contemporary play theorist is Jesper Juul who works on both pure play theory and the application of this theory to Computer game studies. The theory of play and its relationship with rules and game design is also extensively discussed by Katie Salen and Eric Zimmerman in their book: Rules of Play : Game Design Fundamentals.

In computer games the word gameplay is often used to describe the concept of play. Play can also be sexual play between two persons, e.g., Flirting." In music, to "play" may mean to produce sound on a musical instrument, including performance or solitary reproduction of a particular musical composition through one's personal use of such an instrument or by actuating an electrical or mechanical reproduction device.