Here's why:

* Universal Law of Gravitation: Every object in the universe attracts every other object with a force that is proportional to the product of their masses and inversely proportional to the square of the distance between their centers.

* Always Present: Gravity is always present, no matter how small the objects are. Even tiny particles exert a gravitational pull on each other.

* Weak but Long-Range: While gravity is the weakest of the fundamental forces, its effect extends over vast distances. It's what holds the planets in orbit around the sun and the moon around the Earth.

Important Note: While gravity is the only force acting between *any* two objects, other forces can be present depending on the nature of the objects and their interaction:

* Electromagnetic Force: This force arises from the interaction of charged particles and can be attractive or repulsive. It's responsible for holding atoms together, chemical reactions, and light.

* Strong Nuclear Force: This is the strongest force in nature, responsible for holding the nucleus of an atom together.

* Weak Nuclear Force: This force is responsible for radioactive decay.

Let me know if you'd like to explore any of these other forces in more detail!