A tattoo, made by the injection of coloured pigments, was historically used to identify slaves and criminals or for decorative purposes in ancient Egypt. Tattooing was widespread in olden times as evidenced by cave paintings, though it was an expensive process until the 19th century when the electric needle was invented, making it cheaper and faster so even the poor could get tattoos, removing its association with wealth. Now tattoos are commonly done in comfortable salons using hygienic needles and can even be removed by laser technology.