Gravity is the force of attraction between two objects because of their mass.

Here's why:

* Mass: Mass is a measure of the amount of matter in an object. The more massive an object is, the stronger its gravitational pull.

* Distance: The force of gravity also depends on the distance between the two objects. The closer they are, the stronger the gravitational attraction.

So, the more massive two objects are, and the closer they are to each other, the stronger the gravitational force between them.