There are four types of cymbals that are commonly used by drummers all over the world. These are the first options to consider when buying cymbals.
Hi-Hats - Hi-Hats are a pair of cymbals that are mounted on a dedicated stand with a foot-pedal, to control whether the two cymbals are closed together or open. These are often used to play 8th or 16th notes throughout a track. They provide a tight, percussive rhythm which helps pull the overall sound together.
Ride - Ride cymbals are used in a similar way to hi-hats, however, they consist of a single cymbal which rings out and provides a much more open sound than Hi-Hats.
Crash - These provide distinctive accents and help to add dynamics to a track. Crash cymbals have more variation than other cymbal types, some have longer decays (the time it takes for the noise to subside) and others are more punctuated and sharp-sounding.
Splash - Similar to crash cymbals, splash cymbals generally have a dryer and smaller sound than their more powerful counterparts. Although not quite as ubiquitous as the previous three, splash cymbals are a great addition to any setup. They will give you more control over your dynamics, and make your sound more versatile. A great option instead of a second crash cymbal, but not a replacement for your first crash.