A hair toner is a product used to adjust the tone of hair color, either professionally or at home. It is typically used after lightening or coloring hair to eliminate unwanted warm undertones and help maintain the desired color. Hair toner can be in the form of demi-permanent or semi-permanent dyes, tinted shampoos, conditioners, masks, foams, or glosses. It can also be used to add natural or more visible tones to hair. Hair toner works by neutralizing unwanted warm or brassy tones and adding color from the opposite side of the color spectrum. For example, purple toner removes unwanted yellow tinge from blonde hair. Hair toner can be used on all shades of hair to remove brassy tones and add depth and shine. Professional salon toners are more pigmented and effective, and their results last longer. However, pigmented care products are great for maintaining color at home.