I dont get

The Bracket thing?

Never in my life have I heard of this concept. I don't know. I mean, I can semi- understand a football pool (but usually my dad puts my name down because I'm luckier and then I get the money if he wins) but but this bracket thing looks complicated and way too recockulous for my ADD to understand.

Any thoughts?
(and please don't try to explain it to me, I honestly don't care)