Before Apollo and his twin sister were born, their mother was on the run from a giant snake. Juno had sent the snake after knowing Jupiter had had the children. Eventually, once Apollo was born and older, he learned about this. Apollo swore vengeance on the snake, Python.
Apollo was angry, and he wanted to kill Python, so he went to his half brother, Vulcan. Vulcan agreed to make him a golden bow and arrows. Now he needed to find Python.
Delphi is a sanctuary at the center of the Earth. Python would give prophesies there. Apollo wanted to kill Python and have his oracle there.
When Python saw Apollo, he grew angry and struck. Apollo dodged him and notched an arrow. Fighting began to ensue.
The battle was not easily won. Apollo shot an arrow straight between his eyes. Python was dead.
Apollo sang a song of glory after his victory. The Pythian games were made to celebrate Apollos conquering of Delphi. They are held every 4 years in the sanctuary.