The line of gravity of the human body is a vertical line that passes through the center of gravity of the body. The center of gravity is the point at which all of the body's weight is evenly distributed. It is located at about the level of the navel in most adults.

The line of gravity is important because it helps to keep the body in balance. When a person is standing upright, the line of gravity falls within the base of support, which is the area formed by the feet. This creates a stable equilibrium, and the person is able to stand without falling over.

If a person's line of gravity falls outside of the base of support, they will become unstable and may fall. This can happen if a person leans too far forward, backward, or to the side. It can also happen if a person's feet are too narrow or too close together.

Maintaining good posture is important for keeping the line of gravity within the base of support. Good posture means standing up straight with the shoulders back and the head held high. When a person has good posture, their line of gravity will fall in the middle of the base of support, and they will be less likely to fall.