Mehndi (Hindi म, usually denotes the application of henna for body art on the skin.
Mehndi is a beautiful temporary body art form, popularly used in Middle Eastern, North_African and South Asia, is usually drawn, often with intricate patterns and designs, on the hands and feet since the stratum corneum is thickest there (especially for males) and the stain will last for a long period of time.
Although the henna vegetable dye is predominantly applied to the hands and feet of brides, there exist traditions in Bangladesh, Kashmir and Sudan where bridegrooms are also are expected to be tattooed before wedding ceremonies. Also in Rajasthan (northwest India), where mehndi is a very ancient folkart, the grooms traditionally get mehndi designs as elaborate as those for brides.
Once the henna plant is converted to powder, it is mixed with a dark liquid like coffee or tea, lemon juice (to release the dye) and sugar (for consistency) into a paste which is then applied. Depending on how long the paste rests on the skin, the designs last from a few days to two weeks beginning with a red-brown colour and ending with a fading orance presence.
[Note: the term "henna tattoo", American marketing slang, is actually an oxymoron -- a contradition in terms. Henna (mehndi) is a temporary surfacing dying of the skin. Tattoo is the permanent surgical insertion of a pigment underneath the skin.]