The life of a star starts with a giant cloud of gas. The cloud's low temperatures allow the synthesis of molecules.
When gas molecules intercept with each other they create heat energy that later turns into a protostar. A protaster is a formation of a warm clump of molecules.
After the protostar stops receiving materials, it releases a huge amount of energy and makes a T-Tauri star. The warm temperatures in the star aren't enough to support nuclear fission, which makes the star live for 100 million years.
The main sequence phase is when the protons of hydrogen are transformed into atoms of helium, through the process of fission, and due to this process the star releases huge amounts of energy.
Red giants are made when hydrogen atoms stop turning into helium. When this reaction stops, red giants start contracting inward, causing the red giant to expand, have a cooler surface, and a red than yellow appearance.
In this phase most of the star material is balsted away into space, but the core of the star implodes into a neutron star and that converts into a black hole.