A makeup brush is like a magic wand that helps you put pretty colors on your face! You know how you might use a paintbrush to paint pretty pictures? A makeup brush is like that, but for painting on your face.
There are lots of different kinds of makeup brushes. Some are big and fluffy, like a feather duster. These are called powder brushes. They help you put on things like blush and bronzer evenly.
Other brushes are small and thin, like a pencil. These are called eyeliner brushes. They help you put on eyeliner so you don't accidentally poke yourself in the eye!
And then there are flat, dense brushes. These are called foundation brushes. They help you put on foundation smoothly so it looks like you have perfect skin.
When you use a makeup brush, you dip it in makeup, then gently stroke it on your face. It helps you put just the right amount of makeup exactly where you want it. And when you're all done, you can wash the brush so it's ready for the next time you want to use it!