Final answer:
A scientific theory is a well-supported explanation of natural phenomena. It is not a guess but a comprehensive representation of reality based on evidence. Examples include Darwin's theory of evolution.
Step-by-step explanation:
A scientific theory is a well-substantiated explanation of natural phenomena that is supported by a robust body of facts, confirmed through repeated observation and experimentation. In contrast to common everyday usage, where theory might imply a guess or speculation, in science, the term denotes a comprehensive explanation of an important aspect of nature, backed by various converging pieces of evidence. An example of a scientific theory is Darwin's theory of evolution, which provides a factual explanation of species diversity through natural selection. Scientific theories also allow scientists to make predictions about yet unobserved phenomena.
It's important to note that scientific theories have a vast amount of support due to their ability to explain numerous observations. While scientific theories can change, this occurs through a rigorous and lengthy process involving an accumulation of evidence that current theories cannot explain. Therefore, theories in science carry significant weight and are treated as factual as long as they remain unchallenged by new evidence.