Minimum Ignition Energy (MIE) is one of the most important concepts in process safety, especially in industries where flammable substances are present. It refers to the minimum amount of energy required to ignite a mixture of air and fuel, such as gases, vapors, or dust particles. This energy is extremely small and is measured in millijoules (mJ), but even such a tiny spark can lead to serious fire or explosion hazards if not properly controlled.