A boiler is a closed vessel that heats water or other fluids to generate steam or hot water for various applications. It operates by burning fuel, such as natural gas or oil, or using electricity to heat the water. The steam produced can be used for heating buildings, powering machinery, or generating electricity. Boilers come in different types, including fire-tube and water-tube designs, each suited for specific needs. They are commonly found in residential, commercial, and industrial settings. Proper maintenance is essential to ensure safety and efficiency, as malfunctioning boilers can lead to hazardous situations.