Stellar evolution is a complex, interesting process that describes the life cycle of stars, from their birth to their death. The process begins within huge clouds of gas and dust called nebulae. These clouds start to come apart under the influence of gravity. As the cloud decreases in size, the temperature and pressure at the core increase, sometime later igniting nuclear fusion, which is the process that powers a star. Once nuclear fusion begins, a star enters a sequence phase where it spends most of its life, during this stage, the star combines hydrogen into helium in its core, leading to the energy that causes it to shine. Massive stars burn through their fuel super quickly, while smaller stars like the sun can remain in this stuck down phase for billions of years. Once the hydrogen in the core is demolished, the star's evolution turns depending on its mass. Stellar evolution is not just the story of different stars but also the cosmos itself.