Sulfate-free shampoos are less damaging to hair and more gentle than traditional shampoos. Sulfate-free shampoos also protect hair from color damage and contain less chemicals than shampoos that contain sulfates.
Sulfate-free shampoo is used the same way that sulfate-containing shampoos are. The shampoo should be applied to wet hair before the shampoo is applied. The product should be worked through the hair and rinsed thorouhgly before applying conditioner.
Sulfates are grease-cutting ingredients that work like soap to remove oil from the hair. Sodium lauryl sulfate is a common ingredient in shampoo. The ingredient is also what makes the shampoo foam. Sulfate-free shampoos don't produce a foam when used, but can still thoroughly clean the hair and scalp. Sulfates are also used in some facial cleansers and floor cleaners. The chemicals can also irritate the scalp and skin. About.com also states that sodium lauryl sulfates can cause hair follicle damage.