What is the "disk" that encircles a black hole called?

What is the “disk” that encircles a black hole called? An accretion disk.

An accretion disk is a rotating structure of gas, dust, and other matter spiraling around a massive object. Near a black hole, the material usually comes from a companion star, a disrupted star, or gas in the surrounding galaxy. It cannot simply fall straight inward because the material carries angular momentum, causing it to orbit first.

Friction and turbulent magnetic processes transfer angular momentum outward and allow matter to move inward. As it loses gravitational potential energy, the disk becomes extremely hot and can radiate brightly, often in X-rays. This glowing material is why some black holes can be detected even though the black hole itself emits no light.

The disk is not the black hole’s event horizon, and it does not necessarily form around every black hole. A black hole may be nearly invisible if it has little surrounding matter. Accretion disks also occur around young stars, neutron stars, and white dwarfs.