I don't like tattoo, do you?
I don't either. Tattoos are modifications to a person's body 
I learnt it was used during slavery as mark to identity slaves
Tattoo
A tattoo is a form of body modification where a design is made by inserting ink, dyes and pigments, either indelible or temporary, into the dermis layer of the skin to change the pigment. The art of making tattoos is tattooing. 
Tattoos fall into three broad categories: purely decorative (with no specific meaning); symbolic (with a specific meaning pertinent to the wearer); pictorial (a depiction of a specific person or item). In addition, tattoos can be used for identification such as
been used for identification in other ways. As early as the Zhou, Chinese authorities would employ facial tattoos as a punishment for certain crimes or to mark prisoners or slaves. During the Roman Empire, gladiators and slaves were tattooed: exported slaves were tattooed with the words "tax paid", and it was a common practice to tattoo "Stop me, I'm a runaway" on their foreheads. Owing to the Biblical strictures against the practice, Emperor Constantine I banned tattooing the face around AD 330, and the