This is the final Judgement to which all evil people and those who disobeyed God will be present at, every one who ever lived will be judged, apart from those who were caught up in the rapture before the time of tribulation.
When God judges everyone the outcome will determine where they spend eternity. It is the crunch time, at which all who stand will have to give an account of their lives and suffer the consequences. God will open His big book which details the lives of each person and also He will open a little book the book of life and all those who are recorded will be allowed to enter the new eternity with God. All those found unworthy will be sent forever to the lake of fire.