The Otherworld is the name given to the nightmarish parallel universe that materializes through the ancient powers of Silent Hill. It is also commonly referred to as the Alternate World, Another World, Dark World or Nightmare World.
Originally localized in Silent Hill, over time, this supernatural phenomenon extended to neighboring towns, such as Shepherd's Glen and Ashfield. Most games in the franchise feature the protagonists caught in dimensional shifts between this world and the less dangerous (but still hostile) Fog World. Transitions to the Otherworld often occur suddenly and with little warning. The only protagonist who can willingly control the Otherworld shifts is Travis Grady through the use of mirrors.