What is evolution and why it matters?

Evolution is process by which different kinds of living organisms are thought to have developed and diversified from earlier forms during the history of the earth, or in other ways natural selection
and without evolution there would not me so many plants and animals, also did you know without evolution there would be no advance immune system and your systems would not be able to learn about the dangers around you, or help you live in your environment 

The higher you go up the less oxygen there is