BMI stands for Body Mass Index, which is a widely used metric for assessing body weight relative to height. It is important because it provides a quick estimate of body fatness, categorizing individuals into underweight, normal weight, overweight, or obese. While BMI is a useful screening tool, it doesn’t directly assess body fat composition or distribution. Therefore, it should be used in conjunction with other evaluations to better understand an individual's overall health and risks associated with body weight.