Whether or not MonoBehaviour collision messages will be sent by the physics system.
If this property is set to true, M:UnityEngine.MonoBehaviour.OnCollisionEnter(UnityEngine.Collision), M:UnityEngine.MonoBehaviour.OnCollisionStay(UnityEngine.Collision), and M:UnityEngine.MonoBehaviour.OnCollisionExit(UnityEngine.Collision) messages will be sent to the corresponding scripts that have these methods implemented.
If this property is set to false, no M:UnityEngine.MonoBehaviour.OnCollisionEnter(UnityEngine.Collision), M:UnityEngine.MonoBehaviour.OnCollisionStay(UnityEngine.Collision), or M:UnityEngine.MonoBehaviour.OnCollisionExit(UnityEngine.Collision) messages will be sent. This can be beneficial when only the Physics.ContactEvent is used to read contacts as this will stop the physics system from iterating simulation results.
Note: This does not affect trigger events.