BCS, or the Bowl Championship Series, was a system used in American college football to determine the national champion from 1998 to 2013. It involved a combination of polls and computer rankings to select the top two teams for a championship game, along with a series of major bowl games featuring other top-ranked teams. The BCS aimed to create a more definitive national champion compared to previous systems, which often left teams with disputed claims. However, it faced criticism for its reliance on subjective rankings and exclusion of other deserving teams, leading to the establishment of the College Football Playoff system in 2014.