A flare or decoy flare is an aerial infrared countermeasure used by an aircraft to counter an infrared homing ("heat-seeking") surface-to-air missile or air-to-air missile. Flares are commonly composed of a pyrotechnic composition based on magnesium or another hot-burning metal, with burning temperature equal to or hotter than engine exhaust. The aim is to make the infrared-guided missile seek out the heat signature from the flare rather than the aircraft's engines.

An infrared countermeasure (IRCM) is a device designed to protect aircraft from infrared homing missiles by confusing the missiles' infrared guidance system so that they miss their target. Heat-seeking missiles were responsible for about 80% of air losses in Operation Desert Storm. The most common method of infrared countermeasure is deploying flares, as the heat produced by the flares creates hundreds of targets for the missile.