A drum kit, drum set or trap set is a collection of drums and other percussion instruments set up to be played by a single player.

The traditional drum kit consists of a mix of drums (classified as membranophones, Hornbostel-Sachs high-level classification 2) and idiophones (Hornbostel-Sachs high-level classification 1, most significantly cymbals but also including the woodblock and cowbell for example). More recently kits have also included electronic instruments (Hornbostel-Sachs classification 53), with both hybrid and entirely electronic kits now in common use.

A standard modern kit (for a right-handed player), as used in popular music and taught in many music schools, contains:
A snare drum, mounted on a specialised stand, placed between the player's knees and played with drum sticks (which may include rutes or brushes).
A bass drum, played by a pedal operated by the right foot.
A hi-hat stand and cymbals, operated by the left foot and played with the sticks, particularly but not only the right hand stick.
One or more tom-tom drums, played with the sticks.
One or more cymbals, played with the sticks, particularly but not only the right hand stick.

All of these are unpitched percussion, allowing the music to be scored using percussion notation, for which a loose standard exists for the drum kit. If some or all of them are replaced by electronic drums, the scoring and most often positioning remains the same, allowing a standard teaching approach. The drum kit is usually played seated on a drum stool or throne.

Most drummers extend their kits from this basic pattern, adding more drums, more cymbals, and many other instruments including pitched percussion. In some styles of music particular extensions are normal, for example double bass drums in heavy metal music. On the other extreme but more rarely, some performers omit elements from even the basic setup, also dependent on the style of music and individual preferences.