What is a Scientific Theory?

A scientific theory is an explanation of facts.  It explains why and how a set of facts work.  Often there is confusion on the use of the word, theory, because the word by itself can also mean an idea or opinion, and therefore can be up for debate.  A scientific theory, on the other hand, deals with real information that is not debatable.  For example, the theory of gravity explains why objects attract to each other.  If a person lets go of a ball, it will fall.  The theory of evolution explains how organisms adapt in a changing environment over time.  Fossils show this record of change.  Other theories include the big bang theory, climate change theory, and the theory of relativity.