If you've watched the NCAA basketball tournament for many years, it's easy to forget that other people often have no idea what you're talking about when you discuss your "bracket." So let's cover that first.
A bracket, for those who spend these weeks of every year focused on something ridiculous and unimportant like work or family or reading (whatever), looks like this. Before the tournament starts, you fill it in with the teams you think are going to win all the games, right up to the championship. A filled-out bracket looks like this. That one is President Obama's, and it includes both the men's and women's tournaments. This one is mine.
Brackets are often filled out online now, which makes some of us miss the days when they would be printed out or photocopied from newspapers, and we could angrily cross out our picks in the games we got wrong using eight or nine strokes of Sharpie ink on top of each other, while triumphantly circling the ones we got right in red ink.