I wonder how many of those posting on this subject have actually been confined within a Maximum Security Prison. And then, let us narrow it down to how many have actually been involved with a "gang" while incarcerated within a Maximum Security Prison. Gangs are the Tribal Nature of people....all nations of people come from a "TRIBE." gangs are the pack of wolves deep within the forest....the pride of lions....the covey of quail....the flock of geese.
In essence....gangs are a return to the natural state and order of environments; social evolution in real time.

wikipedia definition
A gang is a group of people who, through the organization, formation, and establishment of an assemblage, share a common identity. In current usage it typically denotes a criminal organization or else a criminal affiliation. In early usage, the word gang referred to a group of workmen. In the United Kingdom the word is still often used in this sense, but it later underwent pejoration. The word gang often carries a negative connotation; however, within a gang which defines itself in opposition to mainstream norms, members may adopt the phrase as a statement of identity or defiance. Reports of gang-related homicides are concentrated mostly in the largest cities in the United States, where there are long-standing and persistent gang problems and a greater number of documented gang members—most of whom are identified by law enforcement.

The United States Department of Justice estimates there are approximately 30,000 gangs, with 800,000 members, impacting 2,500 communities across the United States. [1]

Gang is from the past participle of Old English gan "to go". It is cognate with Old Norse gangr "a group of men", and it is in this sense that the word is used today, rather than the older meaningGang - Wikipedia, the free encyclopedia