The branches of science (also referred to as "sciences", "scientific fields", or "scientific disciplines") are commonly divided into four major groups: natural sciences, which study natural phenomena (including fundamental forces and biological life), formal sciences (such as mathematics and logic, which use an a priori, as opposed to factual, methodology), social sciences, which study human behavior and societies, and applied sciences, which apply existing scientific knowledge to develop more practical applications, like technology or inventions.