What begins as a nebula contracts?

What begins as a nebula contracts under the force of gravity, leading to the formation of a protostar. As the material gathers and compresses, temperatures rise, and nuclear fusion ignites in the core, marking the birth of a new star. The surrounding material may form a protoplanetary disk, eventually giving rise to planets, moons, and other celestial bodies. This process is a key part of stellar evolution in the universe.