The moment when the energy generated by fusion in the plasma is equal to the energy required to heat the plasma to fusion temperature. It is denoted as Q = 1, where Q is the fusion energy gain factor, the ratio of the power released by the fusion reaction to the externally supplied power necessary for plasma heating. Scientific breakeven is an important milestone in thermonuclear fusion research. The scientific breakeven was first overcome in December 2022 at the NIF laser-driven fusion facility, when Q = 1.54 was achieved.