What the heck do I do with a kabuki brush?

[Summerhillsquare]

Just that really! Been given one.

You apply makeup with it

But how? And how is it different from a, err, makeup brush?

It IS a makeup brush.
But one with denser bristles for buffing loose powder.

Imagine they're not makeup brushes but paint brushes. Think about how it would work with paint - probably thicker application, more paint, denser strokes.

I use mine for blusher on the apple of my cheek. Works well.