A nozzle is a device used to regulate the direction or properties of a fluid flow as it departs (or enters) an enclosed chamber or conduit, particularly to enhance velocity. A nozzle is often a pipe or tube with changing cross-sectional area that is used to guide or change the flow of a fluid (liquid or gas). The word "nozzle" comes from the fact that they were originally designed to be used on cannon. They are now used on many types of machinery and devices for controlling the flow of fluids. The three main functions of a nozzle are to: 1 reduce the diameter of the stream of fluid entering the chamber, reducing its speed; 2 direct the stream into another location, usually but not always toward the bottom of the tank or container; 3 alter the character of the flow (e.g., sudden changes in direction), typically to create turbulence or other effects. Nozzles can be divided into two general types: static and dynamic. Static nozzles do not move either during operation or when being assembled. Dynamic nozzles operate by having parts slide within each other or otherwise move relative to one another. Winding mechanisms and rotating mechanisms are examples of systems used to provide this motion. Nozzles can also be divided into several different types according to their appearance: simple, complex, and mixed. Simple nozzles have one obvious opening, while complex nozzles may have several openings of varying sizes.