An accretion disk(disc) is an area, usually orbiting a young star, that is full of debris collected from the surrounding space. Protostars, neutron stars, white dwarfs, or black holes are the main bodies that have accretion discs.
An accretion disc is a structure (often a circumstellar disk) formed by diffuse material in orbital motion around a central body. The central body is typically a star. Gravity causes material in the disc to spiral inward towards the central body. Gravitational forces compress the material causing the emission of electromagnetic radiation.