Permanent colors are hair dyes that provide long-lasting results by penetrating the hair shaft. These dyes contain a mix of ammonia and developer, which opens the hair cuticle, allowing the color to bond with the hair. As a result, permanent colors can last until the hair grows out or is cut. Unlike temporary or semi-permanent dyes, permanent colors do not wash out with shampoo. They are ideal for covering gray hair or making significant color changes. Regular touch-ups are necessary to maintain the color at the roots as new hair grows in, ensuring a consistent look over time.