Man-portable air-defense systems (MANPADS or MPADS) are portable shoulder-launched surface-to-air missiles. They are guided weapons and are a threat to low-flying aircraft, especially helicopters and also used against low-flying cruise missiles. These short-range missiles can also be fired from vehicles, tripods, weapon platforms, and warships.

MANPADS were developed in the 1950s to provide military ground forces with protection from jet aircraft. They have received a great deal of attention, partly because armed terrorist groups have used them against commercial airliners. These missiles, affordable and widely available through a variety of sources, have been used successfully over the past three decades, both in military conflicts, by militant groups, and by terrorist organizations.

Twenty-five countries, including China, Iran, Poland, Russia, Sweden, the United Kingdom and the United States produce man-portable air defense systems. Possession, export, and trafficking of such weapons is tightly controlled due to the threat they pose to civil aviation although such efforts have not always been successful.

The missiles are about 1.5 to 1.8 m (5 to 6 ft) in length and weigh about 17 to 18 kg (37 to 40 lb), depending on the model. MANPADS generally have a target detection range of about 10 km (6 mi) and an engagement range of about 6 km (4 mi), so aircraft flying at 6,100 metres (20,000 ft) or higher are relatively safe.

Infrared homing missiles are designed to home-in on a heat source on an aircraft, typically the engine exhaust plume, and detonate a warhead in or near the heat source to disable the aircraft or to simply burst it into flames. These missiles use passive guidance, meaning that they do not emit heat signatures, making them difficult to detect by aircraft employing countermeasure systems.

The first missiles deployed in the 1960s were infrared missiles. First generation MANPADS, such as the early prototypes of the American Redeye, early versions of the Soviet 9K32 Strela-2, and the Chinese HN-5 (A copy of the Soviet Strela-2), are considered "tail-chase weapons" as their uncooled spin-scan seekers can only discern the superheated interior of the target's jet engine from background noise. This means they are only capable of accurately tracking the aircraft from the rear when the engines are fully exposed to the missile's seeker and provide a sufficient thermal signature for engagement. First generation IR missiles are also highly susceptible to interfering thermal signatures from background sources, including the sun, which many experts feel makes them somewhat unreliable, and they are prone to erratic behaviour in the terminal phase of engagement. While less effective than more modern weapons, they remain common in irregular forces as they are not limited by the short shelf-life of gas coolant cartridges used by later systems, requiring only a battery, but the missiles themselves have degraded over the years; For instance, during the Syrian Civil War, the Ahfad al-Rasul Brigades captured 50 Strela-2M missiles (decades past their warranty) from a Syrian Army base in late 2012, but none of them worked.

In 1967, the American FIM-43C Redeye was the first mass-produced design to make use of cooled-detector technology, followed by the Soviet Strela-3 in 1975. They use gas-cooled seeker heads and a conical scanning technique, which enables the seeker to filter out most interfering background IR sources as well as locking on the cooler portions of the jet exhaust plume and other IR-emitting portions of the aircraft, giving them a limited capability of head-on and side engagements.

Third generation infrared MANPADS, such as the French Mistral, the Soviet 9K38 Igla, and the US Stinger B, use rosette scanning detectors to produce a quasi-image of the target. Their seeker compares input from multiple detections bands, either two widely separated IR bands or IR and UV, giving them much greater ability to discern and reject countermeasures deployed by the target aircraft.