clearly as you cannot put an effort to do your own research, I am posting the explanation of scientific theory as written in Wikipedia.
A
scientific theory is a well-substantiated explanation of some aspect of the natural world that is acquired through the
scientific method and
repeatedly tested and confirmed, preferably using a written, pre-defined,
protocol of
observations and
experiments.
[1][2]Scientific theories are the most reliable, rigorous, and comprehensive form of scientific
knowledge.
[3]
It is important to note that the definition of a "scientific theory" (often ambiguously contracted to "theory" for the sake of brevity, including in this page) as used in the
disciplines of science is significantly different from, and in contrast to, the common vernacular usage of the word "theory". As used in everyday non-scientific speech, "theory" implies that something is an unsubstantiated and speculative guess,
conjecture, idea, or, hypothesis;
[4] such a usage is the opposite of the word 'theory' in science.