Hair additions include partial hairpieces and hair extensions. The term "hair addition" is preferred today for the partial hairpieces that used to be called by the jocular terms "toupee" and "rug". The partial hairpiece provides hair replacement only over a defined area of hair loss. It is attached to the scalp with an adhesive, by suction cups or to surrounding hair with clips, hair weaving or bonding with a chemical sealant.
Hair extensions are techniques for bonding human or synthetic hair to existing hair to provide coverage, more density or additional length to existing hair. Techniques include hair-to-hair bonding with an adhesive, sewing or bonding of braids or cornrows to existing hair, hot-bonding with a glue gun, braiding or corn-rowing on netting bonded to underlying natural hair and clip-on extensions. Hair extensions can be adapted to purposes of hair replacement, but the most common purpose is cosmetic enhancement.