What causes molecular clouds to collapse and form stars?

Gravitational attraction causes molecular clouds to collapse and form stars by overcoming internal thermal pressure. When a region of a molecular cloud becomes dense enough, gravity pulls the gas and dust inward, leading to the formation of a protostar. This process is influenced by turbulence, magnetic fields, and external forces like supernova shock waves. As the cloud collapses, conservation of angular momentum causes rotation, leading to the formation of a circumstellar disk where planets may eventually form. Once nuclear fusion begins in the core, a star is born, marking the transformation of a cold cloud into a luminous celestial body.