There are big conferences:
The
big ten
The sec (south eastern conference)
The acc (the Atlantic coast conference)
The big XII
They have their own conference title game and the winners of those conferences get an automatic berth into the playoffs. It is noteworthy that teams typically play 8-9 conference games, and 3-4 non conference games a year.
There are also "
group of 5" less major conferences like the MAC, AAC, conference USA, etc. one of those teams (highest ranked) is guaranteed a spot in the 12 team playoff.
At the end of the year, the 4 "power 5" conference title winners get a "bye" for the first round, and the 8 best ranked teams from thay group, and the 5 major conference make the playoffs. The higher ranked teams get home field advantage.
A playoff bracket could look like this:
The above is called "FBS" division 1 football
FCS (teams outside of the conferences I'm describing) have their own tournament much like the NCAA basketball tourney.