Sodium chloride is more popularly known as common table salt. It is primarily used as a binding and/or thickening agent in skin and hair care products (especially shampoo) and occasionally as an abrasive in salt scrub products. In its crude form, it is a white, crystalline solid.
As for its most common use as a thickener, here are some fun facts: Salt is commonly used to thicken the water phase (also known as the watery) phase of non-soap shampoos, body washes, and facial cleansers. It is a cheap and highly effective, versatile ingredient that is included in several types of cosmetics.
Despite pure salt's potential to dehydrate the skin, the amounts used in skin care and other ingredients present eliminate this problem. As such, sodium chloride is widely considered to be non-irritating and non-drying as used in cosmetics.
The US Food and Drug Administration has placed sodium chloride on its list of substances considered generally recognized as safe. In fact, there is no limit to how much of it can be used in cosmetics, although it is clearly not used anywhere near a 100% concentration! https://www.paulaschoice.com/ingredient-dictionary/ingredient-sodium-chloride.html?q=Sodium%20Chloride&fdid=ingredients