An M-type Main-Sequence Star, also known as a red dwarf, is the smallest and coolest type of star on the main sequence of the Hertzsprung-Russell diagram. These stars have surface temperatures ranging from about 2,400 to 3,700 Kelvin and are characterized by their reddish color. They are the most common type of star in the universe, making up about 70-80% of all stars. M-type stars have low luminosity and burn their hydrogen fuel very slowly, allowing them to have long lifespans, often lasting billions of years. Due to their dimness, they are difficult to observe with the naked eye, but they can host planetary systems, making them of interest in the search for extraterrestrial life.