Henna powder is a natural dye from the dried, ground leaves of the henna plant (Lawsonia inermis), used for centuries to color hair, skin (mehndi), nails, and fabrics, imparting a reddish-brown stain due to the compound lawsone .It's known for conditioning hair, adding shine, and strengthening follicles, often mixed with water or other herbs to create a paste for application.