In modern language, a missile is a self-propelled system, not an unguided self bomb called a rocket (though it can also be guided). The missile has four system components: Aiming or missile guidance, flight system, engine and warhead. Missiles have different types suitable for different purposes: surface to surface and air to surface missiles (ballistic, cruise, anti-ship, anti tank, etc.), surface to air missiles (and Anti Ballistic), air-to-air missiles and anti satellite weapons. All known existing missiles are designed to be propelled by chemical reactions within rocket engines, jet engines or other types of engines during power flight. [need to be quoted] the non self propelled airborne explosive device is usually called a projectile, which usually has a shorter range than the missile

Before the guidance weapons commonly used in British English, missiles were objects thrown at athletes by noisy spectators in sports competitions.

Missiles can be targeted in many ways. The most common method is to use some form of radiation, such as infrared, laser or radio waves, to direct the missile to the target. This radiation may come from the target (such as the heat of the engine or the radio waves of the enemy radar), the missile itself (such as the radar), or a friendly third party. (e.g. radar for launch vehicles / platforms, or laser indicators operated by friendly infantry). The first two are often referred to as "once and for all" because they operate without further support or control of the launch vehicle / platform. Another way is to use the TV Wizard (using visible or infrared) to view the target. Images can be used by human operators who direct missiles to targets, or computers that perform almost the same task. Instead, a more bizarre method of guidance is to use pigeons to guide the missile to its target. Some missiles also have the ability of "jamming source", which can guide themselves to the signal source of launching radar.

Many missiles combine two or more of these methods to improve accuracy and the chance of successful engagement.