Life in this world is a test for everyone. We have been sent in this world to be tested. For every test, there is a result at the end. If the results and the outcome is good then there is a reward for us. But if the results and the outcome is not good then there is punishment.
For this great test, the reward in the hereafter is also great and similarly the punishment is also very severe. And for this punishment, those that fail will have to spend the rest of their time in Jahannam (Hell).
THE COLOUR OF HELL
This is a place of grief and sorrow. Its torments and troubles are far beyond imagination. It was fanned for a thousand years till it became quite red, then it was fanned for a further thousand years till it became white, and again it was fanned for a thousand years till it became black. Now it is quite black and dark.
'Truly Hell is a place of ambush.
For the transgressors a place of dwelling.
They will abide therein for ages.
Nothing cool shall they taste therein, Nor any drink.
Except boiling water, and dirty wound discharges.
An exact recompense (according to their crimes).
For that they used not to look for any account.
But they (impudently) treated Our signs as false.
And all things have We preserved on record.
So taste ye (the fruits of your deeds);
For no increase shall We grant you;
Except in Chastisement.'
(Surah An-Nabaa: 21-30)