BMI stands for Body Mass Index, a numerical value derived from an individual's weight and height. It serves as a generalized indicator of body fat and helps assess an individual's risk for health complications related to weight. A BMI within the normal range suggests a healthier weight, while values indicating underweight or obesity may signal the need for lifestyle changes. Although it is a useful screening tool, BMI does not differentiate between muscle and fat, which is an important consideration when evaluating health.