What Different Types of Perms Can People Get?
Technically speaking, Depeyrot explains that there are three types of perm methods: alkaline, acid, and exothermic. The latter two are part of the "hot" perm treatment process, which means the solution is applied before heat, which then breaks the structural bonds in your hair that make it easier to mold into a curl. A "cold" perm uses alkaline (which contains ammonium thioglycolate, remember Legally Blonde?) to break the same bonds in your hair, and tends to cause slightly less damage than the former.
When you get to the salon, you might learn that there are specific perms with different results depending on the size of the rod your stylist uses. The "body wave" perm, for example, is a looser curl technique that gives you that beachy, straight-from-the-sea effect. "Spiral" perms use longer perm rods to create tighter ringlets, like what you'd expect from Shirley Temple, whereas "pin-curl" perms involves using curlers and pins to make the hair appear wavy and bouncy. The key is to talk with your stylist about the look you're after so they can walk you through the process that's best for you.