Folklorists have created several tools unique to the discipline that allow for the cross-cultural and international study of folk narratives in particular: tale type indexes and motif indexes. The most well-known of these are Aarne and Thompson’s The Types of the Folktale (originally published by Aarne in 1910, and revised in 1928 and 1961 by Thompson, and in 2004 by Uther), and Thompson’s Motif Index of Folk-Literature (originally published 1922-1936; second edition 1955-1958). Thompson’s Motif Index is also available online (see below).
Tale types refer recurring plot patterns in folk-tales. Motifs are the building blocks within these plot-patterns, repeated story-elements. The indexes serve as aids for interpretation and analysis.
There are other tale type and motif indexes as well, with specific geographic or cultural foci. A highlight of what is available is listed below.
For an interesting discussion on motif indexes and tale types, see The Motif-Index and the Tale Type Index: A Critique by Alan Dundes. His article was first published in the Journal of Folklore Research.