In Rifts, a campaign is a continuing storyline or set of adventures typically involving the same characters. The purpose of the continuing storyline is to introduce a further aspect into the game: that of development, improvement, and growth (or degeneration) of the characters. In a campaign, a single session becomes a scene or an act within an overall story arc. At its inception, a campaign may or may not have a defined conclusion. A campaign by definition spans more than one session of play. The gamemaster for a campaign is said to run the campaign.