Frequency regulation in the context of power systems refers to the maintenance of the constant frequency of the electrical grid (e.g., 60 Hz in North America or 50 Hz in Europe). This is crucial for the stability and reliability of the grid. Batteries, especially large-scale energy storage systems, can contribute to frequency regulation by quickly absorbing excess power when the frequency is too high or releasing power when the frequency is too low, thus helping to balance supply and demand in real-time.