Red dwarfs are small, cool stars that are the most common type in the universe. They have a mass between 0.08 and 0.6 times that of the Sun and are much dimmer, making them difficult to see with the naked eye. Their low temperature allows them to burn their fuel slowly, giving them lifespans that can last billions of years. These stars are often found in binary systems, where two stars orbit each other. Red dwarfs can also host exoplanets, some of which may lie in the habitable zone, where conditions could support liquid water and potentially life.