Toning hair dark is a color correction technique that involves applying a semi-permanent dye to hair that has been previously lightened, such as from bleaching or highlighting.
Toning is important for several reasons. First, it can help to even out the color of hair that has been unevenly lightened. Second, it can add warmth or depth to hair that has become too light or brassy. Third, it can help to correct unwanted tones, such as yellow or orange.