Which is considered a form of non-verbal gang communication?

Graffiti is considered a prominent form of non-verbal gang communication as it serves multiple purposes within gang culture. It is often used to mark territory, convey messages about the gang's presence, and display affiliation, rivalries, or violence. The artful, intricate designs characteristic of graffiti can communicate complex ideas and emotions without the need for spoken or written language. This visual representation is particularly powerful within communities, as it can convey messages quickly and efficiently to both gang members and the public.

In contrast, formal greetings, regular meetings, and written procedures are methods of communication that tend to involve verbal or written elements and are not typically classified as non-verbal. They rely on explicit exchanges of information rather than the symbolic, often artistic representation found in graffiti.