The largest bone in the human body is the femur, commonly known as the thigh bone. It is the longest and strongest bone, extending from the hip joint to the knee joint. The femur's primary functions include supporting the weight of the body during activities such as walking, running, and jumping, as well as facilitating movement in conjunction with muscles and ligaments surrounding it. The femur plays a critical role in maintaining balance and posture. Its size and strength allow it to withstand significant forces during physical activities.