"Yggdrasil", often referred to as the World Tree, is a colossal ash tree in Norse mythology that symbolizes the interconnectedness of all things in the cosmos. It has three roots that extend into different realms: one in Asgard (home of the gods), one in Midgard (the world of humans), and one in Helheim (the land of the dead). The tree serves as a bridge between these realms and is inhabited by various creatures, including the dragon Nidhogg and the eagle Veðrfölnir. Yggdrasil's existence is essential to the stability of the Norse cosmos.