Frosting provides an overall salt-and-pepper look, whereas highlighting provides more pronounced stripes of color typically used to frame a person's face. Both hair-dying techniques are similar and involve bleaching hair.
When a person visits the salon to get her hair frosted, she is looking to have a few strands of hair bleached while adjacent hair strands are left untouched. The stylist aims to color-treat the hair evenly so that the end result is a balanced mixture of light and dark, or bleached and natural hair, around the entire head.
When the goal is to add highlights to a person's hair, the stylist bleaches more strands of hair to create pronounced bands of color. Highlights are typically done around the face only, which is called “framing” the face. With highlights, the bleached hair isn't totally blended, but it also isn't overly striking.
Hair can be frosted and highlighted using the cap method. A plastic cap is placed over a person's dry hair and tied under the chin. The cap is full of tiny holes, and the stylist uses a small hook to pull a couple of strands of hair through each hole. The bleach or hair dye is then applied to the hair on the outside of the cap, which prevents chemicals from touching the person's scalp. When the bleaching process is completed, the cap is removed and the hair can be styled.
The other method for frosting and highlighting hair is to use aluminum foil. The stylist selects a few strands of hair and puts them on a square of foil. Bleach is applied to the strands of hair. The foil is then folded up with the bleached hair inside. When the bleaching process is complete, the foil is removed and the hair can be styled.