Apocalyptic Literature

An apocalypse is a genre of revelatory literature with a narrative framework in which a revelation is mediated by an otherworldly being to a human recipient, disclosing a transcendent reality which is both temporal, insofar as it envisages eschatological salvation, and spatial, insofar as it involves another, supernatural world.
John J. Collins “Apocalyptic Literature” from The Dictionary of New Testament Backgrounds

[T]here are a number of traits that are often (though not in every case) found in apocalyptic texts that are less occasionally found in prophetic texts. These traits include the following: narrow eschatology…mediated revelation…unusual imagery…setting of oppression…deterministic view of history and attendant optimism…and pseudonymity and prophecy after the fact.
Tremper Longman III & Raymond B. Dillard An Introduction to the Old Testament (pg. 387-88)

Apocalyptic entails the revelatory communication of heavenly secrets by an otherworldly being to a seer who presents the visions in a narrative framework; the visions guide readers into a transcendent reality that takes precedence over the current situation and encourages readers to persevere in the midst of their trails. The visions reverse normal experience by making the heavenly mysteries the real world and depicting the present crisis as a temporary, illusory situation. This is achieved via God’s transformation this world for the faithful. Paul D. Hanson Visionaries and Their Apocalypses