Eighteen hells

The hell realms (Skt. naraka; Wyl. dmyal ba) which are one of the realms of the six classes of beings are characterized by extremely intense suffering; they consist of eighteen hells:

• the sixteen hells grouped into
  • Eight Hot Hells and
  • Eight Cold Hells;
• the Neighbouring Hells and
• the Ephemeral Hells.

Chökyi Drakpa says in A Torch for the Path to Omniscience:

The cause of being born in any of these eighteen hells could be a vast accumulation of harmful actions perpetrated out of desire or delusion. Even so, a single momentary act such as taking life or speaking harsh words to an exceptional being, when carried out with a mind of intense anger, will propel you straight to the hells.