What is natural selection: Natural selection is the process through which populations of living organisms adapt and change. For example individuals in the population are all different, meaning that the variation can lead to some individuals having better traits that will help them survive in their environment better than others.
How does this relate to evolution?: Well natural selection can lead to speciation. Speciation is when one species changes or evolves into a new and different species.
Background and important people: Charles Darwin is the most important person in the discovery of natural selection. Charles Darwin developed the idea of natural selection after a 5 year voyage. He studied plants, animals, and fossils in South America, along with islands in the Pacific. In 1859 Charles brought the idea of natural selection to the world!
Why do we study it now?: We study natural selection today because it is one of the processes that drives evolution and helps to explain all the diversity of life on Earth. It's also helped us advance in major different ways.