Here's a breakdown:

* Mass: Every object in the universe has mass, which is a measure of how much matter it contains.

* Gravity: Gravity is a fundamental force of nature. It is always attractive, meaning it pulls objects towards each other.

* The more mass an object has, the stronger its gravitational pull. This is why you are pulled towards the Earth, which has much more mass than you do.

So, in short, gravity pulls together any two objects that have mass, regardless of their size, shape, or composition. This includes:

* Planets and stars

* You and the Earth

* A pencil and a book

* Even tiny particles like atoms