Organism that provides bioavailable carbon to ecosystems, particularly in the course of carbon fixing.

Producers generally form the base of ecosystems, supplying reduced organic carbon to numerous heterotrophic organisms. Producers by contrast are autotrophs. The most common produces are photoautotrophs such as plants, eukaryotic algae, and cyanobacteria.

Chemoautotrophs also exist and serve as the base particularly of those ecosystems that are not exposed to substantial levels of light, such as deep sea hydrothermal vents. Together these autotrophs can be described as primary producers, contrasting those organisms involved instead in secondary productivity.

Note that the concept of being a producer and that of ecological production are not identical. As described above, a producer effects what can be described as a primary production, that is, converting carbon dioxide into an organic form of carbon, a form that is now available to heterotrophic organisms.

Secondary productivity, by contrast, is the conversion of this primary productivity into biomass, biomass that is associated with the consumers of producers rather than with the producers themselves.