Glow discharge is a phenomenon that occurs when a gas is ionized by an electric field to create a luminous plasma. There are several synonyms for glow discharge, including corona discharge, plasma discharge, and electric glow. Corona discharge is a type of glow discharge that occurs in the presence of a sharp conductor, while plasma discharge refers to a broader category of plasma phenomena. Electric glow is a more generic term that can refer to any luminous phenomenon caused by electricity. Ultimately, these terms all describe the same fundamental physical process, which is the ionization of gas by an electric field.