Small stars are commonly referred to as dwarfs. More specifically, the smallest type of star is known as a red dwarf. These stars are considerably smaller and cooler than other stars like our Sun.
Red dwarfs are typically less than half the mass of the Sun and have surface temperatures of less than 4,000 Kelvin. Despite their size, they are the most abundant type of star in the universe, making up about 70-80% of all stars.
Interestingly, red dwarfs have very long lifespans, often lasting tens of billions of years, far longer than larger stars which burn out relatively quickly. This longevity is due to their slower fusion processes. So, when we think of small stars, red dwarfs are usually what we are talking about!