Stevia, a natural zero-calorie sweetener derived from the Stevia rebaudiana plant, is widely used as a sugar substitute. It offers benefits such as blood sugar regulation, weight management, and tooth decay prevention. While generally safe in purified forms, it may cause side effects like digestive discomfort and allergic reactions in some people. Stevia is a valuable alternative to sugar for those looking to reduce calorie intake and improve health but should be used thoughtfully alongside a balanced diet.