Science is an ordered knowledge system based on testable explanation and prediction of the form and organization of objective things, and it is systematic and formulaic knowledge. Its object is objective phenomenon, its content is formal scientific theory, and its form is language, including natural language and mathematical language.
Modern science is usually divided into three main branches, which study individual and social natural sciences (such as biology, chemistry and physics) and social sciences (such as economics, psychology and sociology).
And formal science (such as logic, mathematics, computer science) that studies abstract concepts. But whether formal science really constitutes a science is controversial, because they do not rely on empirical evidence. The discipline that uses existing scientific knowledge for practical purposes such as engineering and medicine is called applied science.
Science is based on research, usually in academic or research institutions and government agencies and companies. Scientific research affects the scientific policies of enterprises and countries by developing commercial products, armaments, health products and environmental protection.