The brush works with a soap or a cream to make the lather. The lather is what takes care of your face as you run a razor blade over it so has an important role. You could just smear cream on your face, but a brush will help your soaps and creams last longer. The brush incorporates water and air into the soap to foam it up and the brushing action gets your face ready to shave. Bristles are made from different types of animal hair or synthetic material. Badger hair is regarded as the best because it holds the most water. The more densely the hair is packed the more luxurious the brush, the bigger it is the more fun you have making tons of lather.