Sim (simulated) racing is the collective term for computer software (i.e. a vehicle simulation game) that attempts to accurately simulate auto racing (a racing video game), complete with real-world variables such as fuel usage, damage, tire wear and grip, and suspension settings. To be competitive in sim racing, a driver must understand all aspects of car handling that make real-world racing so difficult, such as threshold braking, how to maintain control of a car as the tires lose traction, and how properly to enter and exit a turn without sacrificing speed. It is this level of difficulty that distinguishes sim racing from "arcade" driving games where real-world variables are taken out of the equation and the principal objective is to create a sense of speed as opposed to a sense of realism.