Tattoos are nonverbal symbols used by gang members to identify a fellow gang member. Knowledge of the types of symbols used in tattoos to abbreviate or obscure affiliation with a specific gang is helpful. This article categorizes these types of symbols as alpha tattoos, numerical tattoos, symbolic/pictorial tattoos, and combination tattoos. Alpha tattoos use letters of the alphabet to depict the name or acronym of the gang. Some examples are AB for the Aryan Brotherhood, AW for Aryan Warrior, and DWB for the Dirty White Boys. Numerical tattoos use a sequence of numbers to represent the gang's name. Numerical tattoos often represent the geographic territory of the gang through street numbers, block numbers, and area codes. Numerical codes are more likely to be found in street-gang tattoos than prison-gang tattoos. Although gangs may migrate to new areas, they often retain the numerical code for the geographic area where they originated. Symbolic/pictorial tattoos are the most difficult to interpret, because there may be no obvious connection between a tattoo's symbols or images and the gang's name or location. Since these symbols are likely to remain the same over long periods, however, it is possible to learn their gang linkage through intelligence information. In such tattoos, the gang symbol may be part of a larger tattoo design that may differ among individual gang members. Combination tattoos combine all the aforementioned categories. As an aspect of gang-related intelligence, the visual documentation and sharing of the meaning of gang tattoos can help to identify gang members and monitor their presence and prevalence in correctional settings.