BMI, or Body Mass Index, is a widely used measure to assess whether an individual has a healthy body weight in relation to their height. It is calculated by dividing a person's weight in kilograms by their height in meters squared (kg/m²). While BMI provides a quick reference regarding body weight categories (underweight, normal weight, overweight, and obesity), it does not account for factors such as muscle mass, body composition, or fat distribution. Therefore, it should be used as part of a comprehensive assessment of health.