The term "body composition" refers to the proportion of fat and lean mass in the body. Lean mass includes muscles, bones, and organs, while fat mass consists of both essential fat necessary for bodily functions and excess fat. Understanding body composition is crucial for assessing health and fitness levels, as it provides a more comprehensive picture than weight alone. Techniques for measuring body composition include skinfold calipers, bioelectrical impedance, and DEXA scans, helping individuals track changes related to diet and exercise.