There are nine realms of the universe in Norse mythology, at the center of which is the cosmological tree, Yggdrasil, also known as The Tree of Life. Some of these realms include Asgard, which is where the gods lived and could only be reached by crossing the rainbow bridge called the Bifrost; Jotunheimr, which was the home of the giants; and Hel, where the dead eventually go.
Because stories were traditionally told and retold orally, Norse mythology has a great deal of variation; even ancient sources differ in order of events and characters. When stories are passed down through generations and translated into other languages, some details do not always stay the same. There are also often several spelling variations of names.
Today, Vikings are seen as mythical Germanic people who were violent and savage, but they were actually Norse explorers and merchants. Some Vikings were pirates and warriors who traveled the world for trade and expansion. During the Viking Age, they conquered parts of Asia, North America, and Europe and were considered powerful beings. “Norse” and “Viking” refer to the same Germanic people from Scandinavia, although they are often depicted as two totally different groups.