Red dwarf stars 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. Due to their low temperature, red dwarfs emit light primarily in the infrared spectrum. They can burn for billions of years, far longer than larger stars, which makes them common in the universe. These stars are often found in binary systems and can host planets in their habitable zones. Some red dwarfs, like Proxima Centauri, are the closest stars to Earth, sparking interest in the search for extraterrestrial life.