A flyback diode is any diode connected across an inductor used to eliminate flyback, which is the sudden voltage spike seen across an inductive load when its supply current is suddenly reduced or interrupted. It is used in circuits in which inductive loads are controlled by switches, and in switching power supplies and inverters.
Flyback circuits have been used since 1930, and they were refined starting in 1950 for use in television receivers. The word flyback comes from the horizontal movement...