Millennialism
The millennium is a 1,000 year period where Christ reigns on heaven and earth, and Satan is bound and thrown into the bottomless pit. It is found in Revelation 20.
The Amillennial and Postmillennial views of eschatology view this "1,000 year" period as symbolic, not representing a literal 1,000 year reign. 1,000 years represents a number of completion, meaning that Christ will reign for the complete amount of time which he is to reign, and he will return immediately after. Christ has already started reigning, when he rose to the right hand of the Father.[1][2] No one knows exactly how long this reign actually is.[3]
The Premillennial view is that Christ will literally reign for exactly 1,000 years on Earth, and literally throw Satan into the void for the duration of that time.
