In Norse mythology, the tree Yggdrasil symbolizes the interconnectedness of all existence. This immense, sacred tree links the Nine Realms, acting as a central axis connecting different worlds, including Asgard, Midgard, and Hel. Yggdrasil represents the cycle of life, death, and rebirth, embodying themes of wisdom, growth, and endurance. The well-being of the realms is intricately tied to this cosmological tree, making it a vital element in Norse mythology.