A musket is a type of gun with a long barrel that soldiers carried and fired from their shoulder. Muskets were important weapons used by many armies from around 1500 until the mid-1800s. Unlike many modern guns, muskets were slow to load: a soldier had to pour gunpowder down the barrel, push in a lead ball with a ramrod, and then fire. The whole process took about 20 seconds, which meant a soldier could fire about three shots per minute.

Muskets were not very accurate either. A skilled soldier might hit a target at 50 yards, but beyond that, aiming was mostly guesswork. That's why armies often fought in long lines standing close together: they relied on many soldiers firing at once rather than precise marksmanship.

The American Revolutionary War was fought largely with smoothbore muskets. By the time of the Civil War, many soldiers were using rifled muskets, which had spiral grooves inside the barrel to spin the bullet and make it fly straighter and farther. Over time, fully modern rifles replaced the musket. A person who carries a musket is called a musketeer, famously featured in Alexandre Dumas's novel The Three Musketeers, about French soldiers in the 1600s.