an example of a protostar provided by NASA
A protostar is a brown dwarf which turns into a small star. The brown dwarf in question does have sufficient mass to sustain a fusion reaction and thereby act as a star, however it does not have enough mass to start the reaction by itself. The process of turning a brown dwarf into a protostar is called "helioforming" (similar to terraforming).
By helioforming the seven largest brown dwarfs in the 34Tauri(2020) star cluster, it was possible to sustain Earth-like life on many more planets and moons than the primary stars themselves could support.