In ancient Norse cosmology, the world was divided into of the nine worlds, or planes. These were distributed into three realms. Often, the worlds were arranged around the world-ash, Yggdrasil.

These are:

In the upper realm:

• Asgard, the abode of the Aesir, ruled by Odin.
• Vanaheim, the abode of the Vanir.
• Alfheim, the world of elves, ruled by Freyr.

Below, connected to the upper realm by Bifrost, the rainbow bridge:

• Midgard, meaning "middle earth," this is the abode of humanity, the physical plane. Midgard is surrounded by the Ocean, the aboud of the world serpent Jormungand.
• Jotunheim, the home of the Jotuns, or giants, and their stronghold, Utgard.
• Svartalfheim, the world of the dark elves, an underground kingdom.

The lowest level, the land of the dead, also has three realms:

• Niflheim, a frozen wasteland, eternal darkness, ruled by Hel.
• Muspelheim, the realm of the fire giants.
• The abode of the dark elves -- dwarves. It is underground.

Related Resources:

• Asatru
  The customs, history, and links on Norse Spirituality on About.com.
• Runes- The Alphabet of Odin
  Discover the ancient oracular alphabet of the Norse, the meanings of the Runic characters, and learn how to do a basic divination with Runes.
• Asatru symbols
  Emblems of Norse religion illustrated and explained.