Deep conditioners, also known as hair masks, are very important for those with dry or damaged hair and are ideal for frequent use. They are also good for those with normal or color treated hair when used at least once a week as a supplement to their normal hair care routine. Deep conditioners are not always necessary for those with fine or limp hair since they will cause the hair shaft to become heavy and weighed down. Leave-in conditioners might be a more suitable solution for combating dry locks when you have thin hair.
The ingredients in deep conditioners are usually more "fatty", containing heavy silicone materials to really coat and protect the hair shaft from the elements, heat, styling and any fracturing of the outer follicle. In the end, this is what keeps the hair from becoming brittle and frizzy. Because the ingredients in deep conditioners are so important, sometimes you might have to spend more for a high-quality product.