The Köppen climate classification has five main climate groups. They are A (tropical), B (arid), C (temperate), D (continental), and E (polar).
These broad groups are based primarily on average monthly temperature and precipitation, with thresholds chosen partly to reflect natural vegetation. Each group can then be divided into more specific climate types using additional letters. For example, Af is tropical rainforest, BWh is hot desert, Cfb is temperate oceanic, Dfc is subarctic, and EF is ice cap.
The groups are not simply five bands of latitude. Elevation, ocean currents, seasonal rainfall, and the position of continents all affect the final code. A mountain summit can have an E climate far from the poles, while a coastal region may remain milder than an inland location at the same latitude.
German–Russian climatologist Wladimir Köppen introduced the system in 1884 and revised it several times, notably in 1918 and 1936. Rudolf Geiger later modified it, producing the widely used Köppen–Geiger classification. Its five-group framework remains one of the most familiar ways to describe global climate patterns.