BMI stands for Body Mass Index, which is a numerical value calculated from an individual's height and weight. It serves as a screening tool to categorize individuals into weight categories, such as underweight, normal weight, overweight, and obese. BMI is significant as it provides a general indication of body fatness and helps assess potential health risks associated with weight. However, it does not account for factors like muscle mass and distribution, which may limit its usefulness in certain cases. Despite its limitations, BMI is widely used in public health and clinical settings for evaluating weight-related health issues.