An event, in CAOS, is a script that an object runs. Events can be triggered in different situations. Creatures or the player interacting with objects can cause events to run - such as pick up scripts or drop scripts (for example, carrots appear on their side when dropped, and upright when held). A timer script, with a TICK set, allows a script to run periodically, such as vending an item at certain times, or allowing bugs and critters to behave in a lifelike manner. In Creatures 2 and later games, physics was introduced, and events such as an object reacting to room boundaries it cannot pass through with a collision event was introduced.