M-dwarfs, also known as red dwarfs, are the smallest and coolest type of main-sequence stars. They have a mass between 0.08 and 0.6 times that of the Sun, making them much less luminous. M-dwarfs burn their hydrogen fuel slowly, allowing them to have long lifespans, often lasting tens of billions of years. These stars are the most common in the universe, accounting for about 70-80% of all stars. Due to their low brightness, M-dwarfs are often difficult to see with the naked eye. They are of great interest in the search for exoplanets and potential habitable zones around stars.