The practice of tattoos and tattooing has different meaning depending on what culture you belong. In early years the most common reason for getting a tattoo is for decoration purposes only.
In some cultures tattoos were used as an identification of the wearer's status in a group. This is still done today by most tribes in Africa, Australia and the South Seas. In certain cultures you can't get a tattoo just because you want one. You will have to earn it. Boys reaching manhood receive one to mark that special occasion. Different styles are applied when men get married and so on. Mokos, Polynesian and Maori facial tattoos, are just applied on Warriors after they did something brave and heroic for the tribe.
The ancient Romans for example used to tattoo their slaves and criminals to recognize them easier, the same with most of the Jews in World War II.
The tattoo culture we have now in the western hemisphere began with sailors traveling to exotic foreign lands. The different tattoo motives they were carrying showed the different places they were stationed. A dragon, for instance, meant the wearer served on a station in China or Japan.
This is the commandment from God regarding such practice.
Leviticus 19:28 You shall not make any cuttings in your flesh for the dead, nor tattoo any marks on you: I am the LORD.
This practice of tattoos and tattooing is a sin against God and must not be entertained by Christians. Body piercing which is a modern trend amongst youngsters (and some oldsters) is also included. It involves the inserting of metal objects anywhere in the body which are not necessary.
Who needs a tattoo or identification? We already have finger prints to differentiate one from the rest or better let the Angels of God do the sealing on the forehead.
Revelation 9:2 Then I saw another angel coming up from the east, having the seal of the living God. He called out in a loud voice to the four angels who had been given power to harm the land and the sea:
Revelation 9:2 Do not harm the land or the sea or the trees until we put a seal on the foreheads of the servants of our God."