They are created from fire.[Hijr 15:26] Indeed We created man from sounding clay made out of black smelly mud.
Some from amongst them have been given the power to take whichever form they wish. Their life spans are very lengthy. The mischievous ones amongst them are called Shaitaan. Like humans, they have intelligence, souls and bodies. They even have children. They eat, drink, live and die.
Aqida: There are also Muslims and Kaafirs amongst them, but in comparison to humans, their kaafirs are much more in number. Amongst their Muslims, there are those who are pious and those who are sinners. They even have Sunni and non-Sunni (Bad Mazhab) amongst them. The number of Faasiqs (open sinners) amongst them is more than that amongst humans.
Aqida: To reject their existence or to say that Shaitaan or Jin only refers to the power of bad is Kufr. To say that there is no such thing as Jin or shaitaan. It is just the power of bad and nothing else is improper.