What is the difference between static and dynamic friction?

Static friction is the force that prevents two surfaces from sliding past each other when they are at rest. It acts on objects that are stationary and serves to hold them in place until the applied force overcomes it. The key characteristic of static friction is that it can adjust its magnitude up to a maximum limit, which is determined by the nature of the surfaces in contact and the normal force acting on them.

In contrast, dynamic friction, also known as kinetic friction, comes into play once the surfaces are in motion relative to each other. Dynamic friction is generally weaker than static friction, which is why it requires more force to initiate movement than to maintain it once the object is sliding.

By understanding these definitions, it's clear why the statement about static friction acting on objects at rest accurately describes its role in mechanical interactions.