Scientific Theory:  

a well-supported explanation of observations.

Scientific Law:

A statement that summarizes the relationship between variables, often expressed via a mathematical equation, which describe or predict a natural phenomena.

Scientific Fact:

an objective and verifiable observation

There is often a misconception that scientific theory is inherently less certain than scientific law or scientific fact, and may be promoted with additional proof. This misconception has damaged public discourse over important issues and even found its way into legislation. A theory is the highest level to which a scientific idea may be elevated. Scientific facts are used to support scientific laws and theories. A theory may include one or more laws.