Here's why:

* Newton's Law of Universal Gravitation: This law states that every particle in the universe attracts every other particle with a force that is:

* Proportional to the product of their masses: The more massive the objects, the stronger the gravitational force.

* Inversely proportional to the square of the distance between their centers: The farther apart the objects are, the weaker the gravitational force.

Examples:

* Earth and the Moon: The Earth's gravity keeps the Moon in orbit.

* You and the Earth: The Earth's gravity pulls you down towards the ground.

* Two stars: Stars in a galaxy exert gravitational forces on each other.

* Even two atoms: Even tiny particles like atoms have a gravitational force between them, although it is extremely weak.

Key takeaway: Gravity is a fundamental force of nature, and it is always present between any two objects with mass, no matter how small or large they are.