Primary productivity is the rate at which energy is converted to organic substances in a region or ecosystem. Energy is converted through autotrophic (self-feeding) organisms, converting solar or chemical energy into biomass. Basically, primary production is generation of food by making organic matter from inorganic matter.
Primary process is photosynthesis (in shallow surface waters), and small amount from chemosynthesis (at deep sea vents and underground). Solar energy is the primary source of energy in the production of biomass in the global oceans, with comparatively trace amount coming from chemosynthetic sources.