If you've ever filled out a bracket for a basketball tournament, you know the thrill of predicting winners and upsets. But there's a whole system behind how those teams are chosen and seeded that might surprise you.
March Madness brackets are trending because Selection Sunday just revealed the 68 teams competing in the NCAA Division I Men's and Women's Basketball Tournaments.
Millions of fans eagerly await this day to fill out their predictions, hoping to pick the perfect bracket.