A group of schools come together and sign a pact with a promise to abide by the pact for three years, the teams for these schools schedule each other in a number of sports, a won/loss system is put in place to keep up with which teams are doing the best and worst, at the end of the season a game or a series of games is held to determine which school had the best team in each sport, rules and procedures are put in place, a group of people in Chicago (the same folks as the Summit) oversee the operations of this group of schools and to assist in compliance with NCAA rules.
This all sounds eerily similar to a conference.