A team time trial (TTT) is a road-based bicycle race in which teams of cyclists race against the clock.
An individual time trial (ITT) is a road bicycle race in which cyclists race alone against the clock on flat or rolling terrain, or up a mountain road such as Alpe d'Huez. There are also track-based time trials where riders compete in velodromes, and team time trials (TTT). ITTs are also referred to as "the race of truth", as winning depends only on each rider's strength and endurance, and not on help provided by teammates and others riding ahead and creating a slipstream. The opening stage of stage race will often be a short individual time trial called a prologue.