A Jotun or Jötun in Norse mythology, is a giant. Groups of Jötun are called Jötnar. They are known for being very large and very strong. Very often they would fight against the gods, but they sometimes mixed. Sometimes gods and Jötnar would marry. Their stronghold is called Utgardr and it is in Jötunheimr, the name for their world. This is one of the nine Norse worlds. Jötunheim is separated from Midgard, or Earth, by high mountains, and big forests. Outside their home world, giants seem to prefer to live in caves.