Brown dwarfs are celestial objects that fall between the characteristics of stars and planets. They are more massive than planets, but do not have enough mass to sustain hydrogen fusion in their cores like stars do. Instead, they primarily emit heat and light from the residual heat left over from their formation. Brown dwarfs are often referred to as "failed stars" because they lack the necessary mass to trigger nuclear fusion and become full-fledged stars. They are typically classified based on their mass, with the lowest mass brown dwarfs being similar in size and composition to gas giants like Jupiter. Research on brown dwarfs helps scientists better understand the formation and evolution of planetary systems, as well as the boundaries between planets and stars. Studies of these objects can provide insights into the physical properties of cool, low-mass objects and how they may differ from both planets and stars.