A well-substantiated explanation of some aspect of the natural world that can incorporate facts, laws, inferences, and tested hypotheses.

Here's why:

* Well-Substantiated: Scientific theories are not just guesses or ideas. They are built upon a strong foundation of evidence from multiple sources, including experiments, observations, and data analysis.

* Explanation: Theories aim to provide a comprehensive understanding of a phenomenon, not just a simple description. They explain why things happen the way they do.

* Aspect of the Natural World: Scientific theories deal with the physical universe, not abstract concepts or personal beliefs.

* Incorporates Facts, Laws, Inferences, and Tested Hypotheses: Theories draw upon established facts, scientific laws (which describe relationships between observable phenomena), inferences (logical conclusions based on evidence), and hypotheses (testable explanations) that have been rigorously tested and supported by evidence.

Important Note:

A scientific theory is different from a scientific law. A law describes a pattern or relationship observed in nature, while a theory explains why that pattern exists.

Example:

* Law: Newton's Law of Universal Gravitation describes the force of attraction between any two objects with mass.

* Theory: The Theory of General Relativity explains how gravity arises from the curvature of spacetime caused by mass and energy.

Theories are constantly being refined and updated as new evidence emerges. They are not absolute truths, but the best explanations we have based on the available evidence.