"Edda" (; Old Norse Edda, plural Eddur) is an Old Norse term that has been applied by modern scholars to the collective of two Medieval Icelandic literary works: what is now known as the Prose Edda and an older collection of poems (without an original title) now known as the Poetic Edda. The term historically referred only to the Prose Edda, but this usage has fallen out of favour because of confusion with the other work. Both works were written down in Iceland during the 13th century in Icelandic, although they contain material from earlier traditional sources, reaching back into the Viking Age. The books provide the main sources for medieval skaldic tradition in Iceland and for Norse mythology.