Deep conditioning is a hair treatment designed to improve the moisture and overall health of hair. It typically involves applying a rich conditioner or mask that penetrates the hair shaft, providing essential nutrients and hydration. This process can help repair damage, reduce frizz, and enhance shine, making it especially beneficial for dry or chemically treated hair. The treatment usually requires leaving the conditioner on for a specific period, often ranging from 15 minutes to an hour. Many people use deep conditioning products regularly, such as once a week, to maintain their hair's strength and softness. Popular brands include Olaplex, SheaMoisture, and Moroccanoil.