This involves the inserting of an ink into the layer of the skin. This was used before in animals mainly for identification purposes only. Body art tattoos now days are used in human body, it is an art that make a particular statement you want to prove if you have a tattoo.
Before, tattoos are used traditionally as a decorative marks, and some used it for an indication of a level in your life or an age counter. Others use it for branding and others just for an art itself, while there are some use it for cosmetic purposes like a permanent makeup or hiding some impurities in the skin, some use it for medical purposes.
Even for religious perspective tattoos can be used, like in Mormon, Islam and even Judaism. Before in early days of tattooing, hygienically speaking, tattooist before doesn't care about having infection and allergies after the tattoos had been made, but today modern tattooist follow some perceptional steps, the tools used should be sterilized and clean, for these are all contaminated with ink and blood. Others have diseases like Hepa A, B, or C or even HIV – AIDS that are all blood contagious diseases. Worry free now, if you follow the right steps and used clean tools before having Tattoos that are for life!