What is a prostar?

There are nine
different stages that a star must pass through before being born.  The first stage is when a
nebula collects and makes a mass of gas and dust then it begins to contract under its own
gravity.  The second stage in the birth of a star is the protostar.  During the protostar stage
the young star has begun to collapse on itself, but not collapsed enough to go through the
nuclear fusion that is required for it to move on to stage 3.  During the protostar stage the
star is protected and must get up to 15,000,000 centigrade degrees.  After that happens the
process moves to stage 3.