Accretion disks are structures formed by diffused material in orbital motion around a central body, such as a star or black hole. These disks are crucial in the process of mass transfer, where matter spirals inward due to gravitational forces, often resulting in the emission of high-energy radiation. The material in an accretion disk can come from various sources, including gas clouds or the remnants of a star. As the matter falls into the central object, it heats up and emits light, making accretion disks observable in various wavelengths, including X-rays and radio waves.