In science, a theory is a reasonable explanation of observed events that are related.
A theory often involves an imaginary model that helps scientists picture the way an
observed event could be produced. A good example of this is found in the kinetic
Line molecular theory, in which gases are pictured as being made up of many small particles
that are in constant motion.
A useful theory, in addition to explaining past observation, helps to predict events
that have not as yet been observed. After a theory has been publicized, scientists design
experiments to test the theory. If observations confirm the scientists' predictions, the
theory is supported. If observations do not confirm the predictions, the scientists must
search further. There may be a fault in the experiment, or the theory may have to be
revised or rejected.