When overload or unforeseen events lead to major grid fluctuations, the resulting drop in voltage is known as “brownout”. The term brownout comes from the dimming experienced by incandescent lighting when the voltage dips. Brownouts occur in power grids with insufficient available balancing capacity, but rarely cause serious damage. However, electronic devices respond differently to brownouts, and may experience a loss of data or functionality. Brownouts are very rare in the pan-European interconnected system, but can also act as a harbinger for a blackout. A controlled brownout is a load reduction in specific segments of the transmission grid that can be carried out in an emergency to ensure the stability of the remainder of the interconnected system. A planned load shedding of this nature is a last resort for stabilising the power grid.