A fuel cell is a device that converts chemical energy from fuels, typically hydrogen, into electricity through a chemical reaction with oxygen. This process produces electricity, water, and heat, making fuel cells an efficient and clean energy source. They are used in various applications, including vehicles, stationary power generation, and portable power systems. Fuel cells operate continuously as long as they have a supply of fuel and oxidant. Unlike batteries, which store energy, fuel cells generate electricity on demand. They are considered a promising technology for reducing greenhouse gas emissions and reliance on fossil fuels, contributing to a more sustainable energy future.