Apocalyptic literature

Apocalyptic literature is a genre of prophetical writing that developed in post-Exilic Jewish culture and was popular among millennialist early Christians.
"Apocalypse" (ἀποκάλυψις) 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 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 exile down to the close of the middle ages.