When people think of the Sweet Sixteen, they think of the NCAA Basketball Tournament. March Madness culls their tournament field down from 64 teams to 16 in the first weekend, then use the second weekend to go from 16 to four so it can crown its national champion in the third week of play.
For baseball, the same principle applies through the first weekend. A 64 team field is culled down to 16 teams, although it obviously goes about it a different way. Once into its "Sweet Sixteen," however, baseball changes, moving into a Super Regional format that will only slice the field in half down to a final eight teams who have a shot at the national championship.
The Super Regionals were introduced in 1999 as part of the expansion and reformatting of the NCAA Tournament. As part of the reconfiguration, the remaining 16 teams who win their regional bracket, will pair off and play a best-of-three series. The eight remaining teams advance to Omaha as participants in the College World Series.
Super Regionals are formed by pairing regional brackets together. One bracket of four teams are paired off against a bracket of four featuring a national seed. There are eight national seeds; the national number ensures that team will host a Super Regional if it makes it that far.
That doesn't necessarily mean the national seed automatically hosts. If the national seed, for whatever reason, cannot host the Super Regional, the bid automatically is given to the other regional winner. So if Miami, for whatever reason, couldn't host the Super Regional round, Boston College would automatically have been awarded the host bid. This is something that happened last year when Missouri State held a national seed and advanced to the Super Regional round. They wound up not being able to host because of a scheduling conflict, so the round reverted to their opponent - Arkansas.
Should there be no national seed available, the super regional will be played at the higher-seeded team's field, unless that higher-seeded team could not host. If the two seeds are the same, then the Super Regional goes to a bid between the two teams.
Whoever wins the best-of-three series this weekend advances to the College World Series, which consists of two four-team brackets. Those eight teams play double-elimination in a similar fashion to the regionals. There will be winner's and loser's brackets with elimination games in that format.
But for now it's simple. Win two out of three this weekend to advance to Omaha.