Moments after the Big Bang, energy begins to condense into matter, protons and neutrons are formed, and then the first element (hydrogen) is formed. Hundreds of millions of years later in stellar nebulae, the hydrogen gas clouds coalesce and, under gravity, form protostars. Nuclear fusion processes begin converting hydrogen into helium. One example of a stellar nursery is the Eagle Nebula.
Acknowledgement: T.A.Rector & B.A.Wolpa, NOAO/AURA/NSF