The National Collegiate Athletic Association, or NCAA, is the national organizing body for intercollegiate athletics in the United States. It is voluntary association of about 1,200 colleges and universities, athletic conferences and sports organizations devoted to the sound administration of intercollegiate athletics. Specific to college hockey, the NCAA sets the rules and regulations regarding scholarships, amateurism, the NCAA Championships, and so on.
The NCAA divides member schools into several divisons, based on various scheduling criteria and scholarship requirements. Division I schools represent the highest level of competition and investment in college athletics. Division II is a less financially intensive division, with lower requirements for the number of sports offered and scholarships allowed. Division III schools offer no scholarships, and place special importance on the impact of athletics on the participants rather than on the spectators.
For college hockey, the NCAA has only two divisions, each with a men's and women's component:
There is also a single Men's Division II conference, but that level of play is not supported by the NCAA and its members all play in Division III conferences as well.
Beacuse of the regional nature of the sport of hockey, as well as the long and rich history of hockey at the collegiate level, the NCAA hockey structure is complex.
(more to be added, note D III schools playing up to D I, scholarship debate, etc.)