Aarne–Thompson classification systems

The Aarne–Thompson classification systems are two indexes used to classify folktales: the Aarne–Thompson Motif-Index (catalogued by alphabetical letters followed by numerals) and the Aarne–Thompson Tale Type Index (cataloged by AT or AaTh numbers). The indexes are used in folkloristics to organize, classify, and analyze folklore narratives. The indexes are an essential tool for folklorists because, as Alan Dundes explains, "the identification of folk narratives through motif and/or tale type numbers has become an international sine qua non among bona fide folklorists". This system was expanded in 2004 into the Aarne–Thompson–Uther classification system (cataloged by ATU numbers).

Use in folkloristics

In his essay "The Motif-Index and the Tale Type Index: A Critique", Alan Dundes explains that the Aarne–Thompson indexes are some of the "most valuable tools in the professional folklorist's arsenal of aids for analysis".Antti Aarne was a student of Julius Krohn and his son Kaarle Krohn. Aarne further developed their historic-geographic method of comparative folkloristics, and developed the initial version of what became the Aarne–Thompson tale type index for classifying folktales, first published in 1910.