Apocalyptic literature is a genre of prophetical writing that developed in post-Exilic Jewish culture and was popular among millennialist early Christians. Apocalypse (Ancient Greek: ἀποκάλυψις, romanized: apokálupsis) is a Greek word meaning "revelation", "an unveiling or unfolding of things not previously known and which could not be known apart from the unveiling". As a genre, apocalyptic literature details the authors' visions of the end times/end of the age as revealed by an angel or other heavenly messenger. The apocalyptic literature of Judaism and Christianity embraces a considerable period, from the centuries following the Babylonian exile down to the close of the Middle Ages. Source: Wikipedia (en)