Detonation has been a known adversary of engine operation for many years. Avoiding detonation conditions is critical since detonation is typically destructive to engine components. Severe detonation often damages pistons, cylinder heads, valves, and piston rings. Damage from detonation will eventually lead to complete failure of the affected part. Detonation can be prevented; however, the conditions which promote detonation are extremely complex and many variables can promote detonation at any one time. This section defines detonation and gives examples of detonation promoters and reducers.