What are branches of science and sub branches of science?

The main branches are the physical sciences and the biological sciences. The physical sciences deal with the natural world we are in, while the biological sciences deal with living organisms. What they have in common is the scientific approach, which makes observations and measurements, forms theories and tests them against the observational evidence.

Scientific theories (other than in mathematics) are not provable and a physical theory is judged by its ability to predict what will happen in particular circumstances when compared with observations. All theories can be replaced by better ones if and when they are discovered.