What are the stages of an average star?

An average star, like our Sun, undergoes several stages in its lifecycle. It begins as a molecular cloud, condensing into a protostar as gravity pulls in surrounding material. Once nuclear fusion ignites in its core, it enters the main sequence phase, where it spends most of its life. Eventually, the star exhausts its nuclear fuel, expands into a red giant, and ultimately sheds its outer layers, leaving behind a white dwarf surrounded by a planetary nebula.