Prison slang is an argot used primarily by criminals and/or detainees in correctional institutions. Many of the terms deal with criminal behavior, incarcerated life, legal cases, street life, and different types of inmates. Prison slang has existed as long as there have been crime and prisons; in Charles Dickens' time it was known as "thieves' cant." Words from prison slang often eventually migrate into common usage, such as "snitch", "ducking", and "Narc."
Prison slang, like other types of slang and dialects, varies regionally.