The Sidewinder air-to-air missile is guided by the heat of its target. It has an infrared homing seeker head that locates the target and guides the missile to it. Here's a more detailed explanation of how Sidewinder missiles work:

1. Detection and Tracking: The Sidewinder missile's seeker head continuously scans the surrounding area for sources of infrared radiation. When it detects a heat source that matches its target parameters, such as the hot exhaust plumes of an aircraft, it locks onto the target.

2. Guidance and Control: Once the seeker head has locked onto the target, the Sidewinder missile's control system takes over. It calculates the target's position and velocity relative to the missile. This information is used to generate guidance commands that steer the missile toward the target.

3. Rocket Propulsion: The Sidewinder missile is powered by a solid rocket motor that provides the necessary thrust to propel it toward the target. The rocket motor burns for a few seconds, giving the missile enough speed and range to reach its target.

4. Warhead and Detonation: The Sidewinder missile carries a high-explosive warhead that is designed to detonate on impact with the target. The warhead is armed after launch and is triggered by the impact or proximity to the target.

5. Maneuvering and Agility: The Sidewinder missile is highly maneuverable due to its aerodynamic design and movable control fins. These fins allow it to change direction quickly and adjust its course to stay on track with the target.

6. Countermeasures: To protect against countermeasures, the Sidewinder missile employs a variety of techniques, such as chaff and flare decoys that confuse the missile's seeker head. It also has counter-countermeasure capabilities to adapt to changes in the target's tactics and defenses.

7. Launch and Deployment: The Sidewinder missile can be launched from different types of aircraft, including fighter jets, attack helicopters, and even unmanned aerial vehicles (UAVs). It is typically mounted on wingtip launch rails or underwing pylons. When the pilot activates the missile, it is released and its motor ignites, propelling it toward the target.

Overall, the Sidewinder missile's combination of heat-seeking guidance, high maneuverability, and warhead effectiveness has made it a successful short-range air-to-air weapon. It has been repeatedly upgraded and improved throughout its service history, making it a staple in the arsenals of many air forces around the world.