Low-mass stars are stars with a mass less than about 2 solar masses (the mass of our Sun). They burn their nuclear fuel slowly, which allows them to have long lifespans, often lasting billions of years. These stars typically fuse hydrogen into helium in their cores and are found in various stages of their life cycle, from main sequence stars to red giants. Examples of low-mass stars include red dwarfs and K-dwarfs. As they age, low-mass stars expand and cool, eventually shedding their outer layers to form planetary nebulae. The remaining core becomes a white dwarf, which will gradually cool over time.