Millennium – comes from the Latin word mille for thousand and Latin word annum for year. Millennium is a thousand year period.

Historical Premillenalism
At the end of the present age there will be great tribulation, followed by the second coming of Jesus Christ. When He comes, the Antichrist will be judged, the righteous resurrected, Satan bound & then will follow a thousand year reign. At the end of the millennium Satan will be released for a short time in which he leads a rebellion against our Lord before been destroyed. The unrighteous will now be raised for judgment followed then by the New Heavens & Earth.

Dispensational Premillenalism (DPM)
This is by far the most complex of the four views, furthermore it is also radically diff from HPM since it teaches that Israel (always separate from the Church) are the recipients of the blessing of the Millennium, not the Church of Christ. They teach that the eschatological watch stopped for the age of Israel at the end of the 69th week at the death of Christ & therefore the rejection of the Messiah & His Kingdom.
There is now a eschatological gap between the 69th & the 70th week (Dan 9) . The clock has stopped ticking for Israel & will not continue to tick again until the last week begins which will be ushered in by a political leader making a covenant with Israel.
Thereafter, the Saints are raptured as Christ's returns in the clouds (not second coming) for His people. In the middle of the seventh week (31/2 years into the 7 year tribulation) the political leader will cease sacrifices in the rebuilt temple & the great tribulation will end with the battle of Armageddon, which will see Christ destroy His enemies.

Now the nations who supported Israel will be gathered into the Millennium Kingdom, those who did not will be cast into the Hades to await the last the last judgment. Christ will reign from His throne in Jerusalem, the Temple will be re built, sacrifices (memorial) re instituted & Israel shall be exalted amongst the nations.
At the end of the 1000 years Satan will be released, unbelievers will be marshalled & the rebellion against Christ will begin. It will be quickly destroyed. Then there will be the last judgment & finally the eternal state ushered in.

Post Millennialism (PM)
PM like AM believe the Millennium is that time between the first & second coming of Christ. They teach that there will be a golden age when the gospel will draw men to Christ in unprecedented numbers, ethnic Israel will be gathered in to receive her Messiah & the nations will be Christinised. There is an expectation of the whole nations being converted. At the end of such a golden age, there will be a brief rebellion, which will be destroyed. Christ
then returns & ushers in the eternal state.

A Millennialism (AM)
Like PM, AM believes that the 1000 tears are symbolic of the time of the last days (from first to second coming). AM expect a parallel growth of both good & evil, side by side. At the end of the Last days there will be great evil & tribulation followed by the second coming, general resurrection, last judgment & the introduction of the eternal state of the new heavens & earth.