A fuel cell is an electrochemical device that converts chemical energy into electrical energy. It produces electricity through an electrochemical reaction between hydrogen and oxygen. There are several types of fuel cells including alkaline, phosphoric acid, molten carbonate, and solid oxide fuel cells. Fuel cells have advantages like high efficiency, zero emissions, and few moving parts. However, they also have disadvantages like high costs and difficulties handling hydrogen fuel. Fuel cells can be used to power vehicles, buildings, and portable electronic devices.