A stirred-tank bioreactor is a vessel used for growing microorganisms or cells under controlled conditions. It typically includes a mixing system, which ensures that nutrients and oxygen are evenly distributed throughout the liquid culture. This design helps optimize the growth and production of desired products, such as proteins or biofuels. These bioreactors can be operated in batch, fed-batch, or continuous modes, depending on the specific requirements of the process. They are commonly used in industries like pharmaceuticals and biotechnology, where microorganisms or cell cultures are cultivated for research and production purposes.