The document discusses different types of forces that act on objects, including contact forces like normal force and friction, as well as non-contact forces like gravitational force, elastic force, and electromagnetic force. It provides definitions and examples of normal force, tension, friction, elastic force, torque, gravitational force, and electromagnetic and nuclear forces. Diagrams of free bodies are introduced as a way to graphically represent all the forces acting on an object in a Cartesian plane. Key aspects of drawing free body diagrams are outlined.