Mehndi is a form of temporary skin decoration that is very popular in South Asia. Mehndi decorations became fashionable in the West in the late 1990s, where they are sometimes called henna tattoos. Henna is typically applied during special occasions like weddings and festivals. It is usually drawn on the palms and feet, where the color will be darkest because the skin contains higher levels of keratin which binds temporarily to lawsone, the colorant of henna. Henna was originally used as a form of decoration mainly for brides.
The term henna tattoo is inaccurate, because tattoos are defined as permanent surgical insertion of pigments underneath the skin, as opposed to pigments resting on the surface as is the case with mehndi.