C-rating indicates a battery's maximum continuous discharge rate. For example, a 2000mAh battery with a 20C rating can safely deliver 40A continuously (2000mAh × 20C = 40,000mA or 40A).
Typical C-ratings:
Higher C-ratings allow for more powerful performance but may reduce flight time. Choose based on your drone's requirements - racing drones need higher C-ratings for quick acceleration, while photography drones can use lower C-ratings for longer flight times.