Henna tattoos are a fun and safe way to explore body art without pain or commitment. Henna is a natural substance that’s been used for centuries to create beautiful, temporary designs on the body – an art form that is called Mehndi (or Mehandi). Mehndi has been a long-standing tradition stemming from many ancient cultures dating back as far as about 5,000 years, but is most known today for its history in India. Today, henna tattoos are still used in religious and wedding ceremonies in India, but has also gained appreciation in other countries as a beautiful art to be appreciated at any time. So, what exactly is henna and where does it come from?
Henna powder is derived from a plant (actually a bush),Lawsonia inermis, commonly found in the Middle East and other areas where the climate is hot and dry. The bush is harvested, dried, and then crushed to make henna powder. The leaves are made into a paste with other additions (tea, oil, lemon, etc.) to heighten the color or make it longer lasting. Henna itself is used for many things such as hair treatment, heat rash relief, and skin conditioner to name a few. The top leaves of the plant are best for Mehndi, while the lower part of the plant is used for the other purposes. Henna paste is what is made to apply henna art designs.
Particular patterns stand for good health, fertility, spiritual enlightenment, wisdom and protection from evil.
In Indian weddings (and many other Asian marriages as well), these elaborate patterns of henna applied on hands and feet of the bride connote special meanings.(Darker colors are thought to mean a successful marriage.)
Those that are drawn on the hands, feet and body of a mother at childbirth events or on brides during bridal showers are all meant for protection. These symbols have been used for centuries, their meanings still intact. These patterns include flowers, flowery trails, chains, plant leaves and other intricate curls embellished with traditional details. 
Natural Henna is NOT Black
Henna powder itself is green in color, but the stain it leaves behind is usually an orange-red color. There are many suppliers now that offer henna in a variety of colors but these are not recommended. Pure henna has had little to no incident of allergic reaction. When colors are added to natural henna, reactions can be mild to severe. Black henna especially has been known to cause serious skin burns as a result of the chemicals added to it to produce the black color effect. Henna is best to be appreciated in its purest form.
Most who are familiar with henna have seen the traditional designs. These beautifully intricate patterns are similar to those used for the marriage ceremonies and other rituals. They usually adorn the hands and feet of the wearer, and require that they remain still for many hours to apply the paste and then allow it to dry. Henna color has been known to take best to the hands and feet due to their dry properties which soak up and hold the color better, but henna can be applied anywhere. How well your skin takes to the henna will depend on each individual’s skin properties. [all above: 2]
Today, henna has been done in many forms including more contemporary designs. Some contemplating a permanent tattoo might apply henna first to see if they like the look before making a permanent decision. Some just enjoy having a temporary design they know will wash off in a few weeks. Whatever your reasons might be for being interested in henna, you are delving into a beautiful form of art rich in culture.
Today, aside from their use in these contexts, the wearing of henna patterns by modern women is more in step with the current fashion. 
Henna designs are different from one culture to another and their significance and meanings are different as well. The countries that rank henna a special place in their culture include India, Pakistan, Sudan, Morocco, Syria, Egypt Persia (Iran), and Malaysia.
For one, the patterns in Arabic are large floral motifs while those in Indian mehndi has fine, lacy designs of flowers and paisley that covers not just the hands but also the forearms. The intricate combination makes it look gorgeous. By the looks of it, wearing henna designs fashionably might be with us for a long while.