M-type stars, also known as red dwarfs, are the most common type of star in the universe. They have a low mass, typically less than half that of the Sun, and a cooler surface temperature, usually between 2,400 and 3,700 Kelvin. This cooler temperature gives them a reddish appearance, and they shine with a faint light. These stars have long lifespans, often lasting tens of billions of years, due to their slow rate of nuclear fusion. M-type stars are important in the search for extraterrestrial life, as many exoplanets have been discovered in their habitable zones, where conditions may support liquid water.