Festival goers arrive for the Glastonbury festival at Worthy Farm, in Somerset, England, Thursday, June 23, 2016. (Photo by Guy Bell/Rex Features/Shutterstock)
A man climbs up a wooden pole to get a prize during celebration of Maslenitsa, or Pancake Week, a pagan holiday marking the end of winter, near Rumyantsevo, Moscow region, Russia, February 26, 2017. (Photo by Sergei Karpukhin/Reuters)
A fighter of Libyan forces allied with the U.N.-backed government runs for cover during a battle with Islamic State fighters in Sirte, Libya, July 31, 2016. (Photo by Goran Tomasevic/Reuters)
Participants run through the streets of the Back Bay during the 16th annual Santa Speedo Run in Boston, Massachusetts, December 12, 2015. (Photo by Brian Snyder/Reuters)
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.