The snare drum (or side drum) is a percussion instrument that produces a sharp staccato sound when the head is struck with a drum stick, due to the use of a series of stiff wires held under tension against the lower skin. Snare drums are often used in orchestras, concert bands, marching bands, parades, drumlines, drum corps, and more. It is one of the central pieces in a drum set, a collection of percussion instruments designed to be played by a seated drummer and used in many genres of music. Because basic rhythms are very easy to learn to play on a snare drum even for children, the instrument is also suitable for the music education for young children and a rhythm band.

Snare drums are usually played with drum sticks, but other beaters such as the brush or the rute can be used to achieve different tones. The snare drum is a versatile and expressive percussion instrument due to its sensitivity and responsiveness. The sensitivity of the snare drum allows it to respond audibly to the softest strokes, even with a wire brush. It can be used for complex rhythmic patterns and engaging solos at moderate volumes. Its high dynamic range allows the player to produce powerful accents with vigorous strokes and a loud metallic click when rimshots are used.

The snare drum originates from the tabor, a drum first used to accompany the flute. The tabor evolved into more modern versions, such as the kit snare (the type usually included in a drum kit), marching snare, tarol snare, and piccolo snare. Each type is a different size, and there are different playing styles associated with each of them. The snare drum that one might see in a popular music concert is usually used in a backbeat style. In marching bands, it can do the same but is used mostly for a front beat.^{[citation needed]} In comparison with the marching snare, the kit snare is generally smaller in length, while the piccolo is the smallest of the three. The snare drum is easily recognizable by its loud cracking sound when struck firmly with a drumstick or mallet. The depth of the sound varies from one drum to another because of the different techniques and construction qualities of the drum. Some of these qualities are head material and tension, dimensions, and rim and drum shell materials and construction.

The snare drum is constructed of two heads—both usually made of Mylar plastic in modern drums but historically made from calf or goat skin—along with a rattle of beads (metal, plastic, nylon, or gut) called "snares" in close contact with it, on the bottom head, which vibrate when the drum is struck. The snares can also be on the top, as in the tarol snare drum, or on both heads as in the case of the Highland snare drum. The top head is typically called the batter head because that is where the drummer strikes it; the bottom head can also be called the snare head (if the snares are located there). The tension of each head is held constant by tension rods. Tension rod adjustment allows the pitch and tonal character of the drum to be customized by the player. Most snare drums have a lever (the strainer) to engage or disengage contact between the snares and the head, and which also permits adjustment of the snare tension. When the snares are disengaged, the sound of the drum resembles a Floor tom. The rim is the metal or wooden ring around the batter head that holds the head onto the drum and provides tension to the head; the rim can also be used in some playing techniques, notably the rimshot, in which the head and rim are struck together with a single stick to create a clicking, or tapping sound.

When the top head is struck, the bottom (resonant) head vibrates in tandem, which in turn stimulates the snares and produces a cracking sound.

The drum can be played by striking it with a drum stick or any other form of beater, including brushes, rute and hands, all of which produce a softer-sounding vibration from the snare wires. When using a stick, the drummer may strike the head of the drum, the rim (counterhoop), or the shell.

The snares can be thrown off (disengaged) with a lever on the strainer so that the drum produces a sound reminiscent of a tom-tom. Rimshots are a technique associated with snare drums in which the head and rim are struck simultaneously with one stick (or in orchestral concert playing, a stick placed on the head and the rim struck by the opposite stick). In contemporary and/or pop and rock music, where the snare drum is used as a part of a drum kit, many of the backbeats and accented notes on the snare drum are played as rimshots, due to the ever-increasing demand for their typical sharp and high-volume sound.

A commonly used alternative way to play the snare drum is known as "cross-stick", "rim click", or "side-stick". This is done by holding the tip of the drumstick against the drum head and striking the stick's other end (the butt) against the rim, using the hand to mute the head. This produces a dry high-pitched click, similar to a set of claves, and is especially common in Latin and jazz music. So-called "ghost notes" are very light "filler notes" played in between the backbeats in genres such as funk and rhythm and blues. The iconic drum roll is produced by alternately bouncing the sticks on the drum head, striving for a controlled rebound. A similar effect can be achieved by playing alternating double strokes on the drum, creating a double stroke roll, or very fast single strokes, creating a single stroke roll. The snares are a fundamental ingredient in the pressed (buzz) drum roll, as they help to blend together distinct strokes that are then perceived as a single, sustained sound. The snare drum is the first instrument to learn in preparing to play a full drum kit. Rudiments are sets of basic patterns often played on a snare drum.