Henna is a natural dye that can be used on hair, skin, and nails. It is derived from the leaves of the henna shrub, Lawsonia inermis. The leaves are dried, ground into a fine powder, and mixed with various liquids, such as water, lemon juice, or tea, to create a paste-like consistency. The paste is then applied to the desired area, where it stains the skin or hair. Henna is typically red or brown in color, but the final color can vary depending on the quality of the henna and the original color of the hair or skin.

It is important to note that some henna products marketed as "black henna" may contain para-phenylenediamine (PPD), a chemical that can cause allergic reactions and skin damage. Therefore, it is recommended to use only natural henna products and avoid black henna.