A scientific theory is a well-substantiated explanation of some aspect of the natural world, based on a body of evidence. It is developed through the scientific method, which involves observation, experimentation, and analysis. Unlike a hypothesis, which is a testable prediction, a theory has been repeatedly tested and confirmed through various experiments and observations. Scientific theories can evolve over time as new evidence emerges. They are not mere guesses or opinions; instead, they provide a framework for understanding complex phenomena. Examples of scientific theories include the theory of evolution, the theory of relativity, and the germ theory of disease.