A cosmetologist works on the nails, skin, and hair of clients, performing various beauty treatment options to help customers achieve their ideal physical appearance. Their duties may include coloring or treating hair, applying makeup or skin care products, waxing, tweezing, and applying artificial nails. Many people in this career also work as hair stylists, but a cosmetologist may specialize in a particular aspect of aesthetic practice, such as manicures and pedicures, skin care, or makeup. Others provide a wide array of cosmetology services to their clients. Every state requires cosmetologists to be licensed to practice their profession.