A katabasis or catabasis (Ancient Greek: κατάβασις, romanized: katábasis, lit. 'descent'; from κατὰ (katà) 'down', and βαίνω (baínō) 'go') is a journey to the underworld. Its original sense is usually associated with Greek mythology and Classical mythology more broadly, where the protagonist visits the Greek underworld, also known as Hades. The term is also used in a broad sense of any journey to the realm of the dead in other mythological and religious traditions. A katabasis is similar to a nekyia or necromancy, where someone experiences a vision of the underworld or its inhabitants; a nekyia does not generally involve a physical visit, however. One of the most famous examples is that of Odysseus, who performs something on the border of a nekyia and a katabasis in book 11 of The Odyssey; he visits the border of the realms before calling the dead to him using a blood ritual, with it being disputed whether he was at the highest realm of the underworld or the lowest edge of the living world where he performed this.