Some very hot types of peppers include, in descending order of heat: the ghost pepper; several kinds of Habanero chilis including the chocolate, orange and red savina; the Jamaican Hot; the Scotch bonnet; and the bird's eye. Other very hot peppers are the Thai, Tepin, Bohemian, Haimen and Yatsufusa peppers.
These peppers have rankings of 100,000 to 2,100,000 Scoville heat units, which were devised in 1912 by Wilbur Scoville. These units are actually a measure of how much capsaicin the pepper has, as capsaicin is the chemical that makes a pepper hot. These levels are also measured through a test called High Performance Liquid Chromotography.