There are three major views on the Millennium of Revelation 20: Premillennialism, Postmillennialism, and Amillennialism. Put simply, Jesus either returns before the Millennium (pre-mil), or after (post-mil); or the Millennium is symbolic of the entire Church age (a-mil).
The Millennium is a sub-view of Revelation, only explicitly mentioned in Revelation 20. Additionally, this chapter is a relatively cursory glance at future events compared to the rest of the book:
There is none of the detail which we have found in the previous portions of the book – for such detail was not necessary to the accomplishment of the design of the book. The grand purpose was to show that Christianity would finally triumph, and hence the detailed description is carried on until that occurs, and beyond that we have only the most general statements. (Albert Barnes, “Notes, Critical, Illustrative, and Practical”, Revelation 20 introduction)
Despite this, many Christians today use Millennial subviews to describe their major framework understanding of Revelation (i.e. Premil = futurism). Historicism defies such categorization, as it is compatible with all three Millennial subviews, and there are major historicist authors that hold to each of the three different subviews.