Depth of Discharge (DOD) is a critical measure in battery technology, indicating the percentage of the battery's capacity that has been used. It's a key factor in determining battery life and efficiency. For example, a DOD of 50% means half of the battery's energy has been used. Batteries with a higher allowable DOD can be used more extensively before needing a recharge, which is particularly important in applications like electric vehicles and renewable energy storage systems. Understanding and managing DOD is essential for optimizing battery performance and lifespan.