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Radiative flux is the net electromagnetic-radiation (EMR) energy passing through a unit area, i.e., from any direction, e.g., watts per square meter. It is conceptually the sum of the intensity (i.e., radiance) from all directions, accounting for angles of incidence. The term irradiance is the equivalent, but is used specifically regarding radiation received by a surface. Note that as a type of energy flux, the energy of any EMR passing in the opposite direction is subtracted. For many instances and uses (e.g., the surface of a star), the ratio is so large that this adjustment has little significance.