Grenade

Historically, a grenade was a small explosive charge that could be thrown by hand. The hand grenade still exists but has evolved, but there are also a number of grenades fired by specialized launchers.

The most common filler for a grenade is explosive, sometimes broken into "offensive grenades" that do not scatter metal fragments, and the more common "defensive grenade" (or grenade without qualifier) that has a blast and fragmentation effect. Other fillers include colored smoke for signaling, white phosphorus for incendiary and screening smoke effect, thermite for incendiary effect, illumination, and tear gas.

Hand grenade

Once past the early stages, there was considerable differentiation of grenade types and designs among nations. For example, the U.S. Army's general-purpose grenades increasingly were shaped more and more like a baseball, assuming that many soldiers could throw that shape accurately. Countries that do not have a sport like baseball often used a "potato masher" type with a cylindrical explosive charge with a concentric, throwing handle, which could get more distance than a ball-shaped grenade.

The fuze of a typical grenade consists of a safety ring, a spring-loaded "spoon", a fuse igniter, and a fuse that leads to the detonator. When the safety ring is pulled, the spoon is free to move, although the user can delay the triggering by holding it down -- this is also common in improvised explosive devices/boobytraps, where the trip wire or other activating mechanism releases pressure on the spoon.

When the spoon is freed, its spring drives an igniter, much like an ordinary match -- creating fire by friction on a sensitized chemical mixture. The flame moves to a pyrotechnic fuse, which gives the delay before explosion, when the flame front reaches the primary explosive detonator and the detonator sets off the main charge. Especially in Soviet-bloc grenades, the fuse may be interchangeable to provide different delays -- effectively zero for improvised explosive devices/boobytraps, 3-5 seconds for general infantry use, 7-12 seconds for long range.

Some grenades, such as thermite used principally to destroy equipment, do not have a time delay as they are not thrown.

Modern

In addition to grenades intended for combat, the "flash-bang" is used for police hostage rescues, military special operations, etc. It disorients with an extremely bright light and loud noise, but rarely does more damage than a broken eardrum. The user can wear eye and ear protection.

Grenade launchers

Dedicated grenade launchers; individual weapons

The U.S. and many other countries use variants of 40mm grenades, fired from:

M79

A weapon carried much like a large shotgun or tear gas gun, the M79 breaks open at the breech to accept a single grenade. In addition to blast/fragmentation, smoke, white phosphorus, and illumination, it accepts a flechette round made up of a bundle of darts for short-range antipersonel work. The other grenades must fly a minimum distance before they arm.

M203

The single-shot launcher attachment for M16 (rifle) or M4 (rifle); they mount under the barrel and fire the same 40mm grenade as the M79

Dedicated grenade launchers; crew-served or aircraft

Mark 19

A belt-fed full-automatic automatic grenade launcher, with versions that can be fired from a tripod, from a mount on a HMMWV or other vehicle, on river patrol boats, and helicopters.

Rocket propelled grenade

A hybrid weapon, generally called a rocket propelled grenade, is typified by the German Panzerfaust or Soviet RPG-7. These have a large warhead, really too large to be thrown by hand, that protrudes from the muzzle of a rocket launcher. The grenade is similar to early anti-tank grenades, in that it is a Munroe-effect shaped charge optimized for armor penetration. They have a range of a few hundred meters.

These weapons are inexpensive and extremely common. They can also be used against ground targets and, with some modifications, helicopters.