Body Mass Index (BMI) is a numerical value derived from an individual's weight and height. It is calculated by dividing a person's weight in kilograms by the square of their height in meters. BMI is commonly used as a simple method to assess whether a person has a healthy body weight for their height. BMI categories include underweight, normal weight, overweight, and obesity. These classifications help identify potential health risks associated with being underweight or overweight. However, BMI does not directly measure body fat and may not accurately reflect the health of all individuals, such as athletes with higher muscle mass.