The Bowl Championship Series (BCS) is a system that was created in 1998 to ensure that the No. 1 and No. 2 teams in college football would always play each other for the national championship. The BCS itself has brought controversy, but it has removed some by eliminating the scenario in which the clear-cut top two teams play in different bowl games, leaving voters to decide the champion if they both win.
The reason something like the BCS was needed in college football is that the system for choosing teams for bowl games was based more on conferences and not rankings. The champion of the Big Ten would always play the champion of the Pac-10 in the Rose Bowl. The champion of the Southeastern Conference would always play in the Sugar Bowl, and so on.
But if the top two teams in the country were from the Big Ten and the Southeastern Conference, they would be forced to play in separate bowl games, and determining a single national champion became difficult. Or impossible -- the year before the BCS came into existence, 1997, saw Big Ten champion Michigan and Big 12 champion Nebraska split the national championship because both were undefeated and both won their respective bowl games, the Rose Bowl and the Orange Bowl.
The BCS uses a complex formula - which includes media and coaches polls and computerized rankings that take into account strength of schedule, among other things - to rank the top teams in college football. The top two teams in the BCS rankings play each other in the national championship game, which rotates between the Rose Bowl, Fiesta Bowl, Orange Bowl and Sugar Bowl. The slots in the other three BCS bowl games are filled by teams from the rankings as well as at-large selections.
While the BCS has, at least for the most part, achieved its goal of pairing No. 1 vs. No. 2, it has done little to appease those calling for a playoff system in college football similar to the exceedingly popular NCAA basketball tournament. The BCS has run into some sort of controversy several times in its brief history.
The most notable was in 2003, Southern California (USC), Louisiana State University (LSU) and Oklahoma each had one loss after the regular season. USC was ranked No. 1 in each of the two human polls in the BCS system, but because of its weaker strength of schedule, it was left out of the national championship game, which featured LSU and Oklahoma. The BCS received a lot of criticism for 2003, and it just got worse in 2004, when five teams finished undefeated for the first time since 1979. There have also been questions regarding the credibility and integrity of the coaches poll that is used in the BCS formula.