Here's why:

* Contact Forces: When objects touch, they exert contact forces on each other. These forces arise from the interaction between the atoms and molecules at the surfaces of the objects.

* Normal Force: A common example is the normal force. When you place a book on a table, the table exerts an upward force on the book, preventing it from falling through. This is a contact force.

* Friction: Another example is friction, which opposes motion between surfaces in contact. If you push a box across the floor, the floor exerts a frictional force on the box, slowing it down.

* Tension: Pulling a rope or stretching a spring involves contact forces called tension.

Why we might think forces are *not* exerted:

Sometimes, we might think forces aren't being exerted because:

* The forces are balanced: If the forces acting on an object are balanced, the object will remain at rest or move at a constant velocity. Even though forces are being applied, there is no net force causing acceleration.

* The forces are very small: Some contact forces, like the air resistance on a slowly moving object, can be so small that we don't notice them.

In short, forces are always involved when objects touch. It's just that sometimes they are balanced or very small, making it seem like no force is being exerted.