How stars power themselvesStars use a method called "Fusion". Fusion is achieved in very very hot conditions and is when two atoms (in this case two hydrogen atoms) collide and turn into a more dense atom (Helium in our case). When this happens it releases large amounts of energy which powers stars.
Stellar NurseryStars are formed in a nebula. They are created when gases and space dusts collapse in on each other creating a proto-star, which further collapses more into either a average star or a massive star
Average starA average star is the first stage and he least dense stage of a star. They are made up of hydrogen and helium. As the hydrogen runs out the inner part of the star begins to contract due to its own gravity and the outer shell starts to expand. Over time it will expand, cool and change colour eventually becoming a red giant.
Red GiantsA red giant is a dying star in its final stage of the star. A red giant is a star that has almost completely run out of hydrogen at its core so it has to draw hydrogen from the outer shell. Once all the hydrogen is fused the star will begin to fuse helium now creating carbon releasing energy. After all the helium is gone the star and carbon is stable the star will start to become a planetary nebula.
Planetary NebulaDuring this stage of the life cycle the outer layers of the star begin to break off and drift away. The star will lose most of its mass this way.
White DwarfThe star has lost most of its mass to the nebula, The star now shrinks and cools and it's now a white dwarf; A stable star with no fusion that will burn its left over heat away for billions of year to come. When all the energy is gone it will enter the final stage of the life cycle
Black dwarfThis is a dead star that has no energy left with perhaps some highly compressed carbon or diamonds.