As this week starts, America's 64 strongest men's varsity basketball teams are lined up at the start of a three-week charge. Weaker ones, or those hit by unlucky breaks and close calls, will be sidelined day by day in a NCAA Division I tournament known as March Madness. Like any phenomenon with millions of passionate fans, the college hoop championship competition may seem larger than life these next few weeks.

The frenzy reaches far beyond campuses and arenas. Anyone anywhere can be a fan. MySpace users can compete for a $10,000 top prize by trying to predict the outcome in a Bracket Challenge. Yahoo has a special mobile phone service with scores, live updates, schedules, commentary and a $1-million contest. A $5 application for the iPhone and iPod touch offers a March Madness features that include live CBS Sports video of all games. Adult fans join workplace wagering pools and sneak peeks at daytime games online.

March Madness is almost inescapable, in other words. For fans, it dominates conversations more than American Idol, Dancing with the Stars and Gossip Girl combined. Excitement comes partly from rooting for local or home state teams, or schools attended by friends or family members. Another hook is the reality TV drama of surprise outcomes - Cinderella stories with buzzer-beating upsets.

What are 'brackets': The NCAA pairs regional teams against each other in the opening rounds based on their 2008-09 records and other factors. Those pairings, just announced Sunday, are called brackets - a reference to the matchup chart newspapers print and post.

Other jargon: In addition to March Madness, the three-week tournament is called the Big Dance. Survivors of the first two rounds are known as the Sweet Sixteen. Those games' winners become the Elite Eight, setting the stage for two pre-championship games featuring the Final Four.

Schedule: The 71st annual tournament begins Tuesday, March 17, and winds up with the Final Four games April 4 at Detroit's Ford Field and a championship showdown two days later.