A scientific theory is a well-substantiated explanation of some aspect of the natural world that can incorporate facts, laws, inferences, and tested hypotheses. Here are some key characteristics:

1. Based on Empirical Evidence: Scientific theories are grounded in observations and data collected through experiments, measurements, and observations. This evidence must be repeatable and verifiable by other scientists.

2. Testable and Falsifiable: A good scientific theory makes predictions that can be tested through experiments or observations. It's also important that a theory can be potentially disproven. If new evidence contradicts the theory, it must be revised or discarded.

3. Explanatory Power: A scientific theory should provide a coherent explanation for a range of phenomena within its domain. It should be able to account for existing observations and make predictions about future events.

4. Predictive Power: A good scientific theory can predict new phenomena that have not yet been observed. These predictions can be tested and help to further refine the theory.

5. Simplicity and Parsimony: While a theory must be comprehensive, it should also be as simple as possible. This is known as Occam's Razor - the simplest explanation is usually the best.

6. Consistency with Existing Theories: New scientific theories should be consistent with well-established theories in other fields. If a new theory contradicts an existing theory, it must provide compelling evidence to justify the inconsistency.

7. Constantly Evolving: Scientific theories are not static. They are constantly being refined and improved as new evidence is gathered and new technologies are developed. This is a process of ongoing scientific inquiry.

8. Not Absolute Truth: A scientific theory is not a fact or absolute truth. It is the best current explanation based on available evidence, but it could be revised or replaced in the future with a better explanation.

It's important to note:

* Scientific theories are different from hypotheses. A hypothesis is a proposed explanation for a phenomenon that needs to be tested, while a theory is a well-supported explanation that has been rigorously tested and validated.

* Scientific theories are not just guesses or opinions. They are carefully constructed explanations based on evidence and logical reasoning.

* The term "theory" in everyday language often means a guess, but in science, it has a much more specific and rigorous meaning.

Understanding the characteristics of scientific theories helps us to distinguish between scientifically valid explanations and unsubstantiated claims.