Mehndi or “Mehendi” is a ceremonial and body art form which originated in the ancient Indian subcontinent.
Muslims in Afghanistan also started to use it as an indication of coming of age.
In the Middle East and Africa, it is common for women to apply henna to their fingernails and toenails and to their hands; using a paste, created from the powdered dry leaves of the henna plant (Lawsonia inermis).
Henna has been used to adorn young women’s bodies as part of social and holiday celebrations since the late Bronze Age in the eastern Mediterranean. Henna was regarded as having “Barakah,” blessings, and was applied for luck as well as joy and beauty. It is a divine experience to adorn your body by henna.
There is always debate why henna is called tattoo. Personally, I do not think Henna has been legally termed as tattoo.
In old days in addition to ornaments on special occasions like wedding, henna was used for body decoration. With globalization, in late 90s, it got popularity in western countries when various celebrities (like Madonna) used henna decoration on their performances.
Since then, it is becoming fashion trend and people are using henna designs just for fun. Since both permanent tattoo and henna are applied in skin for decoration, now it is termed as henna tattoo. But, be assured, it has no relation with permanent tattoo and gets off your skin in few days to couple of weeks.