Theory

Scientifically, theory is hypothesis tested (by experiment, observation) to be true to extent of our current knowledge.
Example
Sky is blue because sunlight is scattered and refracted by particles in atmosphere.
Scientific theories open to further investigation/examination.
Scientific method – body of techniques for investigating phenomena, acquiring new knowledge, or correcting & integrating previous knowledge.
As a result of research, theories can be revised, modified or replaced by new ones.
With a hypothesis, we then devise research project to test hypothesis and come up with a theory. This is focus of research project.