Why do you want a sulfate-free shampoo?

What the heck is a sulfate?

https://en.wikipedia.org/wiki/Sulfate

​Sulfates are an agent in hair products that cleans dirt, chemicals, and oil from your hair. That being said it strips the hair quite harshly of its natural oils as well as everything else. Sulfates are found in the forms of sodium laureth sulfate (SLES) and sodium dodecyl sulfate (SDS). SLES is primarily a foaming agent hence it's popularity in shampoo and SDS is a surfactant which strongly removes oils. 

Why sulfates are bad

http://www.allwomenstalk.com

Every hair strand has a protective layer made of natural oils the scalp and hair secrete. This layer protects the hair from being damaged, sucking up toxins in the air, and shield the hair cuticle from dust and debris. By stripping this layer your leaving your cuticle open and exposed to all of nature's harsh factors. Even though sulfate are very good at cleaning they clean too well and strip the hair of that natural layer of protection. Sulfate are as aggressive to your skin as well as your hair. Your skin also secretes a protective layer of oil on your skin, this is a natural layer that doesn't make your skin greasy, in fact a healthy skin will have a strong layer of oil protecting it. So sulfates strip that layer as well, letting in literally everything into to your pores, no one wants that.

Why Sulfate free shampoos ?

http://www.coastalvirginiamag.com/Fighting-Frizz-with-Summer-Hair-Care/

Since sulfates are so aggressive as a striping agent they are generally frowned upon in shampoos and body washes. But since sulfates are a great foaming agent that produces lots of lather, they are still used in lower end cleansing products. Any good shampoo or body wash will say sulfate free, all higher end shampoos will be sulfate free so if you're buying from your salon, don't worry. The “good stuff” is going to contain a  more organic ingredient base. Using natural cleaners to clear and clean the scalp and hair without causing a harsh effect on the hair, you will also get a richer intake of moisture and protein from organic ingredients. ​

In conclusion sulfates are just too harsh on the hair and skin and should be avoided if possible. You have far more gentle options to clean and take care of your hair that don't involve sulfates and do a heck of a job. So opting for the organic ingredients really will help you out. Both in the integrity, cleansing, and the health of your hair. Healthy hair, happy life