A hi hat or high hat is a set of two cymbals, mounted on a stand and played either by using a foot pedal attached to the stand or with sticks, brushes, or the fingers. Hi hats have two positions: open and closed. Sticks can be used on the hi hat in either the open or closed position, or a combination of both. These cymbals have an indeterminate pitch and are characterized as unpitched percussion.

The hi hat is a standard part of a basic drum set or drum kit, which along with the hi hat includes a bass drum, floor tom, mounted toms, a snare drum, and a crash and ride cymbal. The drum set was invented in the early twentieth century to allow a percussionist to play more than one instrument at once. The drum set is most often associated with rock, jazz, and pop music, but there are also orchestral pieces, for example, the scores for films and musicals, that include a drum set.

The hi hat part is one of the essential elements of a groove, along with the specifications for bass drum, snare drum, and possibly other cymbals. One common technique is to feature the hi hat on the backbeat or on the second or third beat in a waltz, but there are many other approaches depending on the musical style and the inventiveness of the performer. Right-handed players generally place a single hi hat to their left and play it with their right hand, while using the left hand on the snare, but this is not universal. Some players have integrated a second hi hat into their set up, placed either in the center or to their right, in order to incorporate the hi hat sound without having to use cross-sticking.

Hi hat cymbals are capable of a range of sounds, and there are some general categories denoting the style they were designed to go with, such as rock, metal, fusion, and sizzle. There are also more particular descriptions of individual sound. Some of the words used to characterize the stick sound are: crisp, splashy, pure, bright, dark, penetrating, cutting, warm, dry, focused, sizzling, simmering, and deep. They are also often described by the characteristics of their "chick" sound - the sound they make as they're being closed - which may be solid, clean, clear, crisp, cutting, and/or bright.

Hi hat cymbals are sold in matched sets. They are usually made of a bronze alloy that often contains 80% copper and 20% tin, and sometimes silver, and are available in a variety of diameters, including miniature models.