play. Other definitions may focus on play as an activity that must follow certain characteristics including willingness to engage, uncertainty of the outcome, and productivity of the activity to society. Another definition of play from the twenty-first century comes from the National Playing Fields Association (NPFA). The definition reads as follows: "play is freely chosen, personally directed, intrinsically motivated behaviour that actively engages the child." This definition focuses more on the child's freedom of choice and personal motivation related to an activity. Forms Play can take the form of improvisation or pretense, interactive, performance, mimicry, games, sports, and thrill-seeking, such as extreme or dangerous sports (sky-diving, high-speed racing, etc.). Philosopher Roger Caillois wrote about play in his 1961 book Man, Play and Games. Free play gives children the freedom to decide what they want to play and how it will be played. Both the activity and the rules are subject to change in this form, and children can make any changes to the rules or objectives of the play at any time. Some countries in the twenty-first century have added emphasis of free play into their values for children in early childhood such as Taiwan and Hungary. Structured play has clearly defined goals and rules and such play is called a "game". Other play is unstructured or open-ended. Both types of play promote adaptive behaviors and mental states of happiness. Sports with defined rules will take place within designated play spaces, such as sports fields where, in Soccer for example, players kick a ball in a certain direction and push opponents out of their way as they do so. While appropriate within the sport's play space, these same behaviors might be inappropriate or even illegal outside the playing field. Other designed play spaces can be playgrounds with dedicated equipment and structures to promote active and social play. Some play spaces go even farther in specialization to bring the play indoors and will often charge admission as seen at Children's Museums, Science Centers, or Family Entertainment Centers. Family Entertainment Centers (or Play Zones) are typically for-profit businesses purely for play and entertainment, while Children's Museums and Science Centers are typically non-profit organizations for educational entertainment. The California-based National Institute for Play describes seven play patterns: Attunement play, which establishes a connection, such as between newborn and mother. Body play, in which an infant explores the ways in which his or her