It consists of two cymbals mounted on a metal stand, with a pedal mechanism designed such that the cymbals can either be brought together by pressing the pedal, or raised to a predetermined (but adjustable before playing) distance by releasing the pedal. The hi-hat can be played by striking it with a drumstick or brush with the cymbals brought together ("closed"), or apart ("open"), or by using the pedal to forcefully bring the cymbal together.
When struck closed or played with the pedal, the hi-hat gives a short, muted percussive sound. Adjusting the gap between the cymbals can alter the sound of the open hi-hat from a "shimmering", sustained tone to something similar to a ride cymbal.
A right-handed drummer will normally play the hi-hat pedal with their left foot. The traditional hi-hat rhythms of rock and jazz were produced by crossing the hands over, so the right stick would play the hi-hat while the left played the snare below it. However, some top modern drummers do not cross their hands over at all, normally playing the hi-hat and also on occasions a second ride cymbal mounted on the left with the left stick rather than the right.
The hi-hat stand was developed from the low-sock by Gene Krupa in collaboration with Armand Zildjian. The low-sock was a pedal which simply clashed together a pair of similar crash cymbals. They were mounted next to the pedal, so playing them with a stick was not possible.
Up until the late 1960s the standard hi-hats were 14", with 13" available as a less common alternative in professional cymbal ranges and smaller sizes down to 12" restricted to children's kits. In the early 1970s heavy rock drummers began to use 15" hi-hats. In the late 1970s Sabian released their revolutionary 10" mini hats, which were small, heavy hi-hat cymbals intended for close miking either live or recording, and other manufacturers quickly followed. Starting in the 1980s a number of manufacturers also experimented with rivets in the lower cymbal. But by the end of the 1990s the standard size was again 14", with 13" a less common alternative, and smaller hats mainly used for special sounds. Rivets in hi-hats received rave reviews but failed to catch on.
Modern hi-hat cymbals are much heavier than modern crash cymbals, reflecting a continual trend to lighter and thinner crash cymbals as well as to heavier hi-hats. The other change has been that a pair hi-hat cymbals are no longer necessarily similar. More typically the bottom is now heavier than the top, and may also be vented, this being one innovation to have caught on. Some drummers even use completely mismatched hi-hats from different cymbal ranges, of different manufacturers and even of different sizes.
Another recent development is fixed and cable-controlled hi-hats. An extended drum kit will often have a second set of hi-hats, normally smaller than the main ones, mounted to the centre or to the right. These may be fixed closed or connected by a bowden cable to a pedal operated by the drummer's left foot.