Which force always acts in the opposite direction to the movement of an object?

Friction is the force that always acts in the opposite direction to the movement of an object. This force arises when two surfaces interact with each other, and it works to resist the relative motion between them. For example, if you push a box across a floor, friction acts in the opposite direction to your push, slowing the box down. This quality makes friction essential in everyday activities, such as walking or driving, where it provides the necessary grip to prevent slipping.

In contrast, gravity acts downward towards the Earth and does not directly oppose motion unless that motion is vertical. Magnetism can act in various directions depending on the interaction between magnetic poles, and inertia is not a force but rather a property of matter that describes its resistance to changes in motion. These distinctions highlight why friction is unique in that it consistently opposes the direction of movement.