Large cloud fragments into smaller cloudlets that will be stars. Cloudlets are rotating, so as collapse continues, the cloud takes on a flattened disk shape. As collapse continues, the gas becomes denser. Eventually there is enough material for the cloud to become opaque. The cloud now heats up rapidly and emits Infrared light.
Gas pressure slows the collapse to a contraction phase which signals the birth of a protostar.
It may be that slowly rotating cloudlets produce single stars whereas as fast rotating cloudlets may produce binaries owing to 'fission'. Of the nearest 32 stars, about half are single and half binary or triple systems. Magnetic Effects Big gas clouds are 'threaded' by magnetic fields, represented by 'lines of force'. As a result the neutral gas that is undergoing gravitational collapse must filter through the charged particles that are 'attached' to the magnetic fields. A kind of friction results that serves to slow the collapse somewhat.