Explaining the Day of Decision and what occurs during it

Allah says about the Day of Decision -- and it is the Day of Judgement -- that it is at a fixed time, with a set appointment. Its time cannot be added to or decreased. No one knows its exact time except Allah. This is as Allah says,

وَمَا نُؤَخِّرُهُ إِلاَّ لاًّجَلٍ مَّعْدُودٍ

جَزَاءً وِفَاقًا (this being a recompense in full accord [ with their deeds ]..78:26). The punishment given to them in Hell will be based on justice and equity - a fitting recompense - on account of their false beliefs and evil deeds. They will not be wronged in the least.