A boiler is a closed vessel in which water or other fluid is heated. The heated or vaporized fluid exits the boiler for use in various processes or heating applications. Boilers are used in a variety of industries, including power generation, food processing, and manufacturing. Boilers are also used in residential and commercial settings for heating and hot water. Boilers are typically fueled by natural gas, electricity, or oil. The most common type of boiler is the fire-tube boiler, which is a cylindrical vessel with a series of tubes that are heated by a fire on the inside. The fire heats the water, which is then circulated through the tubes. Heat is then transferred from the tubes to the surrounding water, which is then used for heating applications. Boilers can also be used to generate steam, which is then used to power turbines and other machinery. Boilers are an essential part of many industrial and commercial operations, and they are used to provide efficient and reliable heating and hot water.