An octane rating, or octane number, is a standard measure of a fuel's ability to withstand compression in an internal combustion engine without undergoing pre-ignition. The higher the octane number, the more compression the fuel can withstand before detonating. Octane rating does not relate directly to the power output or the energy content of the fuel per unit mass or volume, but simply indicates gasoline's resistance to detonating under pressure without a spark.
A US gasoline station pump offering five different (R+M)/2 octane ratings
Gas stations have gasoline with different octane ratings. Higher numbers indicate that the fuel can better avoid unintended combustions within pistons.
A 1940s US propaganda poster using the term "octane" to emphasise power.
Liquid fuels are combustible or energy-generating molecules that can be harnessed to create mechanical energy, usually producing kinetic energy; they also must take the shape of their container. It is the fumes of liquid fuels that are flammable instead of the fluid.
Most liquid fuels in widespread use are derived from fossil fuels; however, there are several types, such as hydrogen fuel, ethanol, and biodiesel, which are also categorized as a liquid fuel. Many liquid fuels play a primary role in transportation and the economy.
A flaming cocktail works by burning ethanol (grain alcohol), a type of liquid fuel also found in all alcoholic drinks
A worker collecting fuel samples for testing aboard a ship