What actually dark matter is? Simply science explain.

 Dark matter is an invisible substance that makes up about 85% of the total matter in the universe. It does not interact with electromagnetic radiation, so it cannot be directly observed. It is only detected indirectly through its gravitational effects on visible matter, such as stars and galaxies. The exact nature of dark matter is still a mystery and there are several theories as to what it could be, including exotic particles that have not yet been discovered.