Evolution is the process of change over time through natural selection. The document summarizes key evidence and theories of evolution, including: 1. Evidence from the fossil record shows gradual changes in life forms over billions of years. Comparative anatomy and embryology also provide evidence of common descent. 2. Darwin's theory of evolution by natural selection proposed that heritable variations arise by mutation and are selected if they confer a survival or reproductive advantage. This results in adaptation and potentially speciation. 3. Modern theories incorporate genetics and show how variation arises from sexual reproduction, mutation, and recombination of genes, and how selection can change allele frequencies to drive evolution or maintain genetic equilibrium.