A valve is a device or natural object that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various passageways. Valves are technically fittings, but are usually discussed as a separate category. Valves have various usages, including controlling water for irrigation, industrial uses for controlling processes, residential uses such as on/off and pressure control to dish and clothes washers and taps in the home. In this module one can learn about the types of valves, functions, parts, advantages & disadvantages of different valves, selection of valves, specification, suitability of valve, operation and maintenance.