ORLANDO, Fla. — Here’s a primer on what people mean when they talk about the three most common types of firearms: handguns, rifles and shotguns.

HANDGUNS

Glock 9-mm semiautomatic pistol

Developed at the turn of the 20th century, semiautomatic pistols remained less popular than six-shot revolvers until the mid-1980s. That’s when U.S. police departments switched to the pistol’s high-capacity magazines, fearing officers were being “outgunned” by similarly armed criminals. Glock handguns remain popular as police sidearms and for self-defense.

It fires one bullet with each pull of the trigger. The exploding gunpowder sets off a series of actions that propel the bullet through the barrel, automatically eject the empty cartridge (or bullet casing), load a fresh cartridge and cock the pistol for the next shot. Magazines inserted into the pistol grip typically hold 10 to 33 cartridges, with some models holding up to 100.

Cost: about $600

Smith & Wesson .38 Special revolver

The rotating cylinder holds six cartridges. It fires one bullet with each pull of the trigger. Empty cartridges must be ejected manually. The “38 Special” revolver was the standard police sidearm for decades. Revolvers remain popular for self-protection and are available in a wide range of models for concealment as well as target shooting.

Cost: $300 to $750, depending on condition and model

RIFLES

Bushmaster .223-caliber semiautomatic assault rifle

The Bushmaster is one of many brands of AR-15 civilian versions of the M-16 assault rifle first used by U.S. troops in Vietnam. The M-16 and later military models can fire in semiautomatic or fully automatic mode — which means the gun will continue firing with a single trigger pull until pressure is released or the weapon runs out of cartridges.

Known for accuracy and light recoil, the AR-15 is a popular sporting rifle and self-defense weapon whose rounds can typically penetrate body armor. Magazines hold 10 to 100 cartridges.

Bushmaster rifles were used in the mass killings at Newtown, Conn., and Aurora, Colo., as well as the Christmas Eve ambush of firefighters in upstate New York and the 2002 Beltway sniper killings around Washington, D.C.

Cost: $1,500 and up

Marlin .22-caliber bolt-action rifle

The .22 Long Rifle is one of the most popular in the U.S. for target shooting and small-game hunting. The Marlin’s tubular magazine under the barrel holds about 15 cartridges and fires once with every pull of the trigger. Each empty cartridge must be manually ejected by pulling back the bolt, which also inserts a new cartridge when closed.

Cost: about $300, depending on condition and model

SHOTGUNS

Remington Wingmaster 870 pump-action shotgun

This 12-gauge shotgun fires shells loaded with a variety of pellets, from tiny birdshot to pencil-eraser-diameter buckshot. Commonly used for hunting, it holds up to four shells in a tubular magazine. Fires once with every pull of the trigger. Each fired shell must be ejected manually before loading a new shell.

Cost: about $300 and up, depending on condition and model

Mossberg 500 A pump-action shotgun

This 12-gauge shotgun is used for self-defense at close distances. It usually is fired from waist level, as it does not have a butt stock for more accurate firing from the shoulder position. It holds up to five shotgun shells.

The sound of a pump-action shotgun “racking” a round is commonly characterized by law enforcement as the “scariest sound a criminal can hear.” Fires once with every pull of the trigger, and empty shells must be manually ejected by sliding back the pump action before loading a new shell.

Cost: about $350