Closed, open and pedal hats
Hi-hats carry the rhythm between the kick and the snare, so they are the part listeners hear as groove. Closed hats give the steady eighths or sixteenths; open hats mark the offbeats in disco and house; pedal hats add a soft chick when the foot closes the cymbals.
For trap and drill, short, bright hats work best because they are often programmed in fast rolls and triplets. For lo-fi and boom bap, darker, slightly distorted hats sit better behind the drums.
Tips
Filter the low end out of every hat to keep the mix clean, and pan them a little to one side as a real kit would. If you use an open hat, set your sampler to let the closed hat choke it. Check the licence badge before you build a whole loop around a sound.