The Theory of Evolution is a scientific explanation for how species change over time. It is based on the principles of natural selection and genetic diversity. Natural selection is the process in which organisms best adapted to their environment are more likely to survive and pass their advantageous traits on to their offspring. Genetic diversity, on the other hand, refers to the range of genetic variation within a population which enables individuals to better adapt to changing environments. Over long periods of time, these processes can lead to the development of new species. The theory of evolution has been supported by vast amounts of scientific evidence, and is considered one of the most well-established principles in biology.