In science, a broad, natural explanation for a wide range of phenomena. Theories are concise, coherent, systematic, predictive, and broadly applicable, often integrating and generalizing many hypotheses. Theories accepted by the scientific community are generally strongly supported by many different lines of evidence-but even theories may be modified or overturned if warranted by new evidence and perspectives. To learn more, visit Science at multiple levels.

Capable of being tested scientifically. An idea is testable when it logically generates a set of expectations about what we should observe in a particular situation. Ideas that are not testable cannot be investigated by science. To learn more, visit Testing scientific ideas.

Designed innovations that serve some practical function. Science and technology frequently contribute to one another — with scientific advances leading to the design of new technologies, and new technologies enabling new observations or tests that advance scientific knowledge. To learn about how science benefits technology, visit Fueling technology.

In science, an observation or experiment that could provide evidence regarding the accuracy of a scientific idea. Testing involves figuring out what one would expect to observe if an idea were correct and comparing that expectation to what one actually observes. To learn more, visit Testing scientific ideas.