Overunity devices are theoretical machines that claim to produce more energy than they consume, effectively achieving a greater output than input. This concept challenges the fundamental laws of physics, particularly the first law of thermodynamics, which states that energy cannot be created or destroyed. Proponents of overunity devices often cite examples like perpetual motion machines, which have been historically debunked. Despite numerous claims and experiments, no overunity device has been scientifically validated or accepted by the mainstream scientific community, as they typically violate established principles of energy conservation.