Population I stars likely started forming around 8 to 10 billion years ago, with the process continuing to the present day as new star-forming regions develop in galaxies. These third generation stars are composed of the remnants of Population II stars. The majority of the stars adorning the Milky Way today belong to this third generation. To be clear, even these stars are mostly the first two elements of the Periodic Table: Hydrogen and Helium with only about 2% heavier elements. Our Sun is a Population I star.