[razark]

Evolution is both a theory and a fact.

The fact: Populations change over time. This has been observed in the wild, as well as under laboratory conditions.

The theory: Populations change over time due to selection, either by natural means, or by conditions imposed by humans.

The fact of evolution is what is observed. The theory is the model built to explain why the fact is observed. As more facts are observed, the theory is modified to account for the facts.

The same with gravity. The fact of gravity, I drop something, it falls down. The theory of gravity explains why it happens. The theory may be wrong, but it is the best explanation for the observed facts.