Jinns were created from fire as we were created from soil. Allah, the Exalted, says
(And He created Jinn from the flame of the fire)
[Holy Quran, Chapter: 55, Verse: 15]

They were created before the creation of mankind, as Allah, the Exalted, says
(And We have created Jinns before, from the smokeless fire)
[Holy Quran, Chapter: 15, verse: 27]

They were created from fire, but it does not mean that they are like fire or close to its characteristics. In fact, they have solid bodies like us. It is, because when a Jinn wanted to interrupt the prayer of the Prophet Muhammad (Peace be upon him), with power given by Almighty Allah, he caught him and strangled him.
[See, Muslim: Imam Muslim, Vol: 2, Page: 99]

During this action, the Prophet (Peace be upon him) felt the cool of the saliva of the Jinn’s mouth too
[See, Fat hul Bari: Allama Ibn-e-Hajar Asqalani, Vol: 1, Page: 555]

The above recorded event clearly shows that they have solid bodies like us even though we can not see them.

There are several kinds of Jinns. It is narrated from the Prophet (Peace be upon him) that Jinns are of three kinds; First, those who have wings through which they can fly, second, those who are in the form of snakes and spiders, third, those who travel and stay somewhere.
[See, Fat hul Bari: Imam Ibn-e-Hajar, Vol: 2, Page: 345]

In addition, Imam Badruddin Aaini has descriptively recorded in his book their several kinds and named some of them too.

1. Ghaul or Ifreet: They are very dangerous kinds of Jinns. They live in barren Places. They can easily change their physical appreances.
2. Saulaat: They live in forests
3. Ghadaar: They usually live in and around Yemen and Egypt.
4. Walhaan: They live in Islands.
5. Shaq: They are equal to the half of the length of mankind.
6. Some are familiar to mankind and do not hurt them
7. Some are in the form of lizards
8. Some are in the form of dogs.

[See, Umdatul Qari: Allama Badruddin Aaini, Vol: 15, Page:183-184]

They are of the several creations of Allah, the Exalted. As mankind, they are also created to worship their Lord. As it is mentioned in the Holy Quran:
(And I have only created Jinns and men that they may worship Me.)
[Holy Quran, Chapter: 51, Verse: 56]

However, like in human-being, not all of them on righteous path. Some of them upon listening to the Holy Quran, accepted its message. Holy Quran itself describes this historical event saying:
( Say, it has been revealed to me that some of the Jinns listened to my recitation attentively and said, “We have heard a wonderful Quran. That guides towards righteousness, so we have believed in it, and we shall never associate anyone with our Lord. )
[Holy Quran, Chapter: 72, Verse: 1, 2]

Like mankind some of them are pious and nice and some are wicked, giving hard times to others. Allah, the Exalted described their acceptance saying:
and some of us are otherwise. (And that there are some amongst us righteous We are divided into different ways. )
[Holy Quran, Chapter: 72, Verse: 11]

With the power given by Allah, the Exalted, to them, they are able to carry out some astonishing hard work that is impossible for any ordinary human-being to do. Such as Ifreet, a most powerful Jinn; he was ready to bring the giant throne of Queen of Saba to Prophet Sulaiman (Peace be upon him) in some seconds. Holy Quran describing it says:
( One big evil Jinn said, “I will bring to you that throne before you rise from your sitting; and undoubtedly, I am powerful over that, trust worthy. )
[Holy Quran, Chapter: 27, Verse: 39]

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