A perm, short for permanent wave, is a cosmetic hair treatment that alters the shape of your hair, giving it curls or waves that can last for several months. Perms are a popular way to change up your hairstyle, or to add body and volume to flat hair.
Perms have been around for centuries, but the modern perm was developed in the early 1900s by a German hairdresser named Karl Nessler. Nessler's perm used a chemical solution to break down the hair's natural bonds and then reshape it into curls or waves. This process is still used today, although the chemicals used have been improved over the years to be less damaging to hair.