Ignition is the process of starting something burning or setting it on fire. When you strike a match, that moment when the flame first appears is ignition. In a car, turning the key or pushing the start button triggers ignition in the engine: a spark ignites the fuel, creating tiny explosions that power the vehicle forward.

Scientists use ignition to describe the exact moment a substance reaches the temperature where it bursts into flame, called its ignition point or ignition temperature.

Ignition can also describe the moment when something begins or takes off. When a rocket launches, mission control announces “We have ignition!” as the engines roar to life. You might hear someone say an idea was the ignition for a successful project, meaning it sparked everything that followed. Whether it's starting an engine, launching a spacecraft, or beginning something important, ignition is that crucial moment when potential energy transforms into action.