What are jinn according to Islam?

Jinn are a created species, distinct from humans and angels, mentioned throughout the Quran with an entire surah named after them.

What the Quran establishes:

• They were created from smokeless fire, before humans
• They have free will, and are accountable in the same way humans are
• Among them are Muslims and disbelievers, righteous and corrupt. Surah Al-Jinn records a group who heard the Quran and believed
• They can see us in ways we generally cannot see them
• Iblis was among them, not among the angels
• They live, marry, reproduce and die

Belief in their existence is part of belief in the unseen, which the Quran makes a defining characteristic of the believer in the opening verses of Surah Al-Baqarah.

What the Quran does not do is present them as a preoccupation. They exist, they are accountable, and they are not something believers are told to focus on. Much of the detailed folklore in circulation has no basis in the sources at all.