A drum is a musical instrument consisting of one or two stretched membranes, called heads, held taut across a bowl-shaped or tubular frame, called a shell, and sounded by percussion; that is, by striking the instrument with the hands or with sticks.

The drum shell holds the skin or skins taut and also acts as a resonator. Drum shells that are basically tubular vary in their actual shape, from cylindrical, as in a bass drum; to barrel-shaped, as in some drums of China and India; to goblet-shaped, as in the single-headed Middle Eastern darabuka; to hourglass shaped, as in the double-headed Japanese tsuzumi. If the drum shell is so shallow that it cannot act as a resonator, as on a tambourine, the drum is called a frame drum.

Single-headed drums with bowl-shaped shells are called kettledrums. Usually tunable and played in pairs, they include the European orchestral kettledrums, or timpani; the naqqara of Islamic countries and their medieval European relative, the nakers; and the baya, one of a pair of kettledrums, played in Indian classical music.

Drum shells are commonly made of wood, metal, or pottery. The heads, made of animal skin or plastic, are fastened to the shell by nails, glue, buttons, pegs, laces, or a cord whip-hopped around the border of skin that overlaps the shell. Double-headed Western orchestral and band drums, such as the snare drum, tenor drum, and bass drum, usually have two hoops for each head, one around which the excess skin is lapped, another pushing against the first hoop and holding the skin taut. Lacing may be done in a W or Y pattern, adding more tension to the heads. In modern drums, the lacing may be replaced by tension screws attached to the top hoop.

The drums obviously demand a very good sense of time, but also require a sense of tone. A fact unknown to most beginning guitarists, bassists, and pianists is that drums must be tuned. Tympani drums are based on the predication that their tune may be changed by way of foot pedals, roto-toms share this quality, and turning them may change their tune. Acoustic drums are tuned when the head is changed, and tune is obtained by the tightening or loosening of the head.

Percussion music is unlike those of the piano, guitar, and bass because it is written in different notation. This is usually a turn-off to other musicians because of its ominous appearance (as it looks like the proverbial “chicken scratch”).

The drums are extremely difficult to play because the percussionist must use all four appendages (and not all at the same exact time). The left hand is primarily used to play the snare, the left foot for the high-hat and/or one bass-kicker, while the right hand is used to strike the high-hat or ping cymbal, and the right foot for the bass kicker. A skilled drummer can do four things at once (all on different accents of a divided beat).

Drums are essential to keeping the beat and accenting both “up” and “down” beats. Percussion is the focal point of the beat and may also be melodic, such as wind chimes, chimes, bells, xylophones, and pianos. Without percussion, even skilled musicians can wander from the beat if the time signature changes in the composition or if the musician plays for an extended period of time.