BMI stands for Body Mass Index, a numerical value calculated from an individual's height and weight. It is used as a screening tool to categorize individuals into different weight categories, such as underweight, normal weight, overweight, and obese. Healthcare providers utilize BMI to assess health risks associated with weight, helping in identifying possible issues like diabetes and cardiovascular diseases. Though it has limitations, such as not considering muscle mass, BMI remains a widely used indicator in clinical settings.