You start with a hypothesis, which is an educated guess as to what happens under a certain set of circumstances, based on preliminary findings. Next, you devise an experiment or series of experiments designed to test the hypothesis. Based on the results of your experiment, you revise your hypothesis and continue to test it via experimentation. The revised hypothesis that is confirmed by empirical results is a theory. However, part of the scientific method is re-testing theories as a new information becomes available and revising theories to take new information into account.