ATU Index
The Aarne-Thompson-Uther Index is a catalog of international folktale types used by folklorists to identify and compare story patterns across cultures.
The ATU Index, officially titled 'The Types of International Folktales,' was originally compiled by Finnish folklorist Antti Aarne in 1910, expanded by American folklorist Stith Thompson in 1928 and 1961, and revised by German folklorist Hans-Jörg Uther in 2004. It classifies folktales into over 2,000 numbered types organized into broad categories: Animal Tales (1-299), Tales of Magic (300-749), Religious Tales (750-849), Romantic Tales (850-999), and Tales of the Stupid Ogre (1000-1199), among others. This system allows researchers to trace how the same basic story appears across different cultures and centuries.