What is defined as the point where ignition occurs and fuel begins to burn?

The point where ignition occurs and fuel begins to burn is known as the "flash point." This term specifically refers to the lowest temperature at which a substance can vaporize to form an ignitable mixture in air. When the temperature of the fuel reaches its flash point, it produces enough vapor that, when exposed to an ignition source, will ignite.

While the other terms relate to fire and combustion, they do not specifically describe the actual temperature or conditions when fuel starts to burn. The source of ignition is about the means by which fire starts, the point of origin refers to the specific location where a fire starts, and the fire triangle is a model that illustrates the three elements needed to start and maintain a fire: heat, fuel, and oxygen. Each term contributes to fire science, but none define the moment combustion begins as accurately as the flash point.