The driver's clothing was color-coded in accordance with his faction, which would help distant spectators to keep track of the race's progress. According to Tertullian, there were originally just two factions, White and Red, sacred to winter and summer respectively. As fully developed, there were four factions, the Red, White, Green, and Blue. Each team could have up to three chariots each in a race. Members of the same team often collaborated with each other against the other teams, for example to force them to crash into the "spina" (a legal and encouraged tactic). Drivers could switch teams, much like athletes can be traded to different teams today.