High octane fuel is often used in high performance vehicles that require premium gasoline. It is also used in aircrafts. The higher the octane number, the more compression the fuel can withstand before detonating.
Detonation is when the air-fuel mixture in the cylinder ignites prematurely. Parts of the air/fuel mixture can start to ignite too early. These mini fireballs then collide and create a knocking noise. When this happens, it’s called engine knock or ping.
Detonation can damage your engine by causing pre-ignition, which is when hot spots in the combustion chamber cause the air/fuel mixture to ignite too soon. Pre-ignition can lead to piston damage and overheating.
Higher octane fuel helps prevent these problems because it has a higher resistance to heat and pressure, so it’s less likely to detonate prematurely.