The calendar reaches mid-March, so you know what that means. And it's no problem if you don’t – we're here to help you understand why basketball fans experience "madness." The mania began recently as college teams battled for league and conference championships or strong season finishes. Those outcomes affect selections made Sunday as NCAA officials determined who qualifies for a nearly three-week tournament starting Tuesday, as well as match-ups in the earliest rounds.

The field of 68 teams includes basketball powerhouses such as Kansas, Villanova, North Carolina, UCLA, Kentucky, Louisville and Gonzaga, as well as lower-tier hopefuls flirting with the possibility of an upset in what's called the Big Dance. A David-beats-Goliath surprise happens most years. The number of competitors shrinks daily with opening rounds in nine cities, followed by four regional quarter-finals March 23-26 in Kansas City, San Jose, Memphis and New York. Semifinal and championship games featuring the Final Four teams are April 1 and 3 at the University of Phoenix Stadium in Arizona.

Fans will watch livestreams and telecasts on CBS, TBS, TNT and truTV – yes, sometimes sneaking peeks at school and at work. (OK, that happens often). This type of hard-core rooting, plus betting pools that may be stone-cold serious or just-for-fun blind draws of team names, are why it's dubbed March Madness. There's also a NCAA women's tournament, with selections announced Monday, that runs through a March 31 and April 2 championship series in Dallas.

Off-court impact: The tournament is a big business, generating more than 95 percent of the NCAA's revenue from broadcast rights, a share of ticket fees, sponsorships and merchandise.

Blogger says: "The NCAA men's basketball tournament field is loaded this year, featuring many stars that we'll see suiting up for NBA teams in the fall." -- Paul Kasabian, Bleacher Report