An Ampere-Hour (Ah) is a unit of electric charge that measures the amount of current a battery can deliver over a specific period. It indicates how long a battery can provide a certain amount of current before it is depleted. For example, a battery rated at 1 Ah can supply 1 ampere of current for 1 hour. This measurement is crucial for understanding battery capacity in devices like smartphones, electric vehicles, and other electronics. Higher Ah ratings generally mean longer usage times between charges, making it an essential factor when choosing batteries for various applications, including solar energy systems and portable electronics.