Here's why:

* It's a force: Gravity is one of the four fundamental forces in the universe, alongside the strong force, weak force, and electromagnetic force.

* It governs motion: Gravity is responsible for the attraction between objects with mass, causing objects to fall towards the Earth, planets to orbit stars, and galaxies to clump together.

* It's described by mathematical laws: Newton's Law of Universal Gravitation and Einstein's Theory of General Relativity mathematically describe the behavior of gravity.

* It's a subject of ongoing research: Scientists continue to study gravity, trying to understand its nature and its role in the universe.

So, gravity is not just an example of physics, it's a cornerstone of the field.