Battery life refers to the duration a battery can power a device before needing to be recharged. It is typically measured in hours or cycles, indicating how long the battery can sustain its charge under specific conditions. Factors affecting battery life include the device's energy consumption, the battery's capacity, and usage patterns. Different devices, such as smartphones, laptops, and electric vehicles, have varying battery life expectations. For instance, a smartphone may last a day on a single charge, while an electric vehicle can travel hundreds of miles. Understanding battery life helps users manage their devices more effectively.