Henna is a plant. The leaves of the plant are dried and then crushed into a powder. The powder is then made into a paste that when applied to the skin, produces a beautiful reddish-brown stain. Henna is also used as a natural reddish hair dye. Once the paste has been applied to the skin, it should be left on from 4-8 hours. Keeping the paste slightly moist and warm will help the paste create a darker stain. Henna tattoos are a fun, natural and safe type of temporary tattoo. One of the funniest aspects of henna tattoos is that you can change your tattoo designs often. These tattoos are also a great way to try on a tattoo design to see how you like it before you get it permanently tattooed on your body.