M-dwarfs, also known as red dwarfs, are the smallest and coolest type of star in the universe. They have a mass between 0.08 and 0.6 times that of the Sun and emit less light and heat. Due to their low temperature, M-dwarfs shine with a reddish hue and can have lifespans that last billions of years, making them the most common type of star in our galaxy. These stars are often found in binary systems and can host planets in their habitable zones, where conditions might allow for liquid water. The search for extraterrestrial life often focuses on M-dwarfs, as their long lifespans provide ample time for life to potentially develop. Notable examples of M-dwarfs include Proxima Centauri and Barnard's Star.