Define evolution. How does it occur? Describe how fossils provide us evidences in support of evolution 

Explanation

Evolution is a gradual process leading to heritable changes over several generations. It occurs due to natural selection, mutation or genetic drift.
The preserved traces of fossils help in 
• establishing evolutionary traits among organisms and their ancestors (homologous structures).
• establishing the time period in which organisms lived from the position of fossils in the layer of the rocks
• documenting the existence of now-extinct species that are related to present-day species.