M dwarfs, also known as red dwarfs, are the smallest and coolest type of main-sequence stars. They have a mass less than half that of the Sun and a surface temperature ranging from about 2,500 to 4,000 degrees Celsius. Due to their low luminosity, M dwarfs are often difficult to see with the naked eye, but they make up about 70% of the stars in our galaxy, the Milky Way. These stars have long lifespans, often lasting tens of billions of years, which is much longer than larger stars like G-type stars (e.g., our Sun). M dwarfs are of great interest in the search for exoplanets and potential extraterrestrial life, as their habitable zones are closer to the star, making it easier for planets to maintain liquid water.