Keira Knightly attends the UK Gala Premiere of “A Dangerous Method” at The Mayfair Hotel on January 31, 2012 in London, England. (Photo by Stuart Wilson/Getty Images)
Tattoos are commonly used among criminals to show gang membership and record the wearer's personal history—such as his or her skills, specialties, accomplishments and convictions. They are also used as a means of personal expression. Certain designs have developed recognized coded meanings. The code systems can be quite complex and because of the nature of what they encode, the tattoo designs are not widely recognized.