Career Mode is the main gameplay aspect of Guitar Hero. In Career Mode, the object of the game is to successfully play every song in a group known as a tier, and then play the encore song for that tier. Once that is accomplished, the player can move on to the next tier, until the final tier is reached. When the final encore song is played, the career is beaten, and the player can now focus on either the bonus songs, or boosting their career score.
Also, a tier must be reached in Career Mode before it can be unlocked in Quick Play, which makes career mode the first thing that most players go to when they get a new Guitar Hero game.
Career score is one of the best ways to determine one's skill at Guitar Hero. Formerly, Career Score was the total of one's scores on all of the songs, across all difficulties. For example, if one has 180,000 points on a certain song on Expert, but 195,000 on that same song on Hard, the Hard score would be counted toward the Career Score.
However, in Guitar Hero III, there were difficulty specific Career Scores. That means that only Expert songs would count toward the Expert Career score and so on. In Guitar Hero III, a 14 million career score is considered a very big achievement, since it requires Full Comboeing nearly every song in the game.