The Koppen climate classification system is one of the most widely used climate classification systems. It uses six letters to divide the world into six major climate regions, based on average annual precipitation, average monthly precipitation, and average monthly temperature. The letters are a,b,c,d,e,h. A is for tropical humid, b is for dry, c is for mild mid-latitude. D is for servere mid-latitude, e is for polar, and h is for highland. Each category is further divided into sub-categories based on precipitation and temperature. <3lacey<3