* Opposing Force: Friction is a force that opposes the relative motion between two surfaces in contact. It acts in the opposite direction to the object's motion.

* Energy Conversion: When friction acts, it converts some of the object's kinetic energy (energy of motion) into heat energy. This heat is dissipated into the surroundings.

Here are some examples of friction slowing down objects:

* Sliding a book across a table: The friction between the book and the table converts the book's kinetic energy into heat, causing it to slow down and eventually stop.

* A car braking: The friction between the brake pads and the rotors converts the car's kinetic energy into heat, bringing the car to a stop.

* A ball rolling across the floor: The friction between the ball and the floor slows the ball down until it eventually comes to rest.

Important Note: While friction typically slows objects down, there are also instances where friction can *increase* the speed of an object. This happens when friction acts in the direction of motion. For example, a runner uses friction between their shoes and the ground to propel themselves forward.