Population II stars are older stars that formed in the early universe, typically more than 10 billion years ago. They are primarily found in globular clusters and the halo of galaxies. These stars have low metallicity, meaning they contain fewer elements heavier than hydrogen and helium, which indicates they formed before many of the heavier elements were created in later generations of stars. Unlike Population I stars, which are younger and found in the disk of galaxies, Population II stars are often red giants or horizontal branch stars. Their characteristics help astronomers understand the formation and evolution of the universe, as they provide insights into the conditions present during the early stages of star formation.