Stars form in cold clouds when gravity overcomes pressure, creating protostars that glow in infrared.

As gas falls in, core temp rises; a protostar gathers mass from a surrounding disk and initiates fusion.

Hydrogen fusion balances gravity; mass determines brightness, temperature, and lifetime along the main sequence.

Hydrogen fuel wanes, shells burn, and the star swells into a red giant before helium ignition reshapes it.

Mass decides fate: white dwarfs, neutron stars, or black holes, and their roles in galaxies.