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. It is the ratio of the power released by the fusion reaction to the externally supplied power necessary for plasma heating. The condition when Q = 1 is also referred to as scientific breakeven. This is an important milestone in thermonuclear fusion research. If enough electricity is produced from the heat generated by the fusion reaction to keep the entire fusion facility running, we speak of an engineering breakeven. Only after it is exceeded can the fusion facility begin to operate as a power plant that generates and supplies electricity to the grid. The scientific breakeven was first overcome in December 2022 at the NIF laser-driven fusion facility, when Q = 1.54 was achieved.