1. Normal Force: This is the force exerted by a surface perpendicular to the object in contact with it. For example, if you place a book on a table, the table exerts an upward normal force on the book to counteract gravity.

2. Friction: This force opposes motion between two surfaces in contact. It can be static (when the object is not moving) or kinetic (when the object is moving). Examples include the friction between your shoes and the ground, or the friction between a car's tires and the road.

3. Tension: This force is transmitted through a string, rope, cable, or similar object when it is pulled taut. It acts in the direction of the pull. For instance, if you pull on a rope tied to a bucket, the tension in the rope pulls the bucket upwards.

4. Applied Force: This is a force applied directly to an object by a person or another object. For example, pushing a box across the floor, hitting a baseball with a bat, or pulling a wagon.