Norse mythology is stories about Gods and Goddesses who lived in ancient Scandinavia a very, very long time ago. They told stories that explained how the world was created, and why things happened the way they did.
There was a big tree called Yggdrasil that connected all the different realms of the world - like Earth, Asgard where the Gods lived and other places too. At the top of the tree was Asgard where the most important Gods lived, and at the bottom was Hel where the souls of dead people would go.
The main God of Norse mythology was Odin, he had one eye and was very wise. He could see everything that was happening all around the world. The other important Gods were Thor, the God of Thunder, and Loki, a tricky God who could shape-shift into different animals.
The stories of Norse mythology included all kinds of things like battles between the Gods, magical artifacts that could do incredible things, and stories that explained why things like lightning and earthquakes happen.
Norse mythology was passed down through stories and songs long before anyone wrote it down, so there are many different versions of the stories. But they are still really interesting and fun to learn about!