Abscisic acid (ABA) is a plant hormone that plays a crucial role in helping plants respond to stress. It helps regulate various processes, such as seed dormancy and the closure of stomata, which are tiny openings on leaves. When a plant experiences drought or other stress, ABA levels increase, signaling the plant to conserve water and energy. This hormone is essential for plant growth and development, influencing processes like fruit ripening and leaf senescence. By managing these functions, abscisic acid helps ensure that plants can survive in changing environmental conditions, making it vital for agriculture and ecosystem health.