Evolution is the gradual process in which something changes int o a different and usually more complex or better form. It is the change in the genetic composition of a population during successive generations, as a result of natural selection acting on the genetic variation among individuals, and resulting in the development of a new species.
Evidence for evolution:
Paleontology: the study of fossils. Is evidence for evolution because the oldest fossils are simple animals and plants
Geographical distribution: each continent has its own characteristic types of life.
Comparative anatomy: the study of similarities and differences in body structures. Similarities are used to determine the evolutionary relationships between different types of living things. The more simliar in structure, the more closely related they are.
Comparative embryology: the study of embryos (similar to comarative anatomy in theory)
Genetic sources: studies of cell biology have shown many similarities in cells.