In Norse mythology, Yggdrasil is the immense World Tree that connects the nine realms, serving as the cosmic axis around which all of existence revolves. Its roots extend into the underworld, its branches reach the heavens, and it is home to various mythical creatures, including the dragon Níðhöggr, who gnaws at its roots. Yggdrasil symbolizes the interconnectedness of life, death, and fate, playing a central role in Norse cosmology as the foundation of the universe and the balance of order and chaos.