Nozzles are devices that are meant to control the characteristics(especially to increase velocity) and most importantly the direction of a fluid flow as it exits or enters an enclosed chamber.
A nozzle is often a tube or a pipe of varying cross sectional area that can be used to modify or direct the flow of a fluid. When it comes to the characteristics of the gas or the fluid that they control, one can say that there are many. They usually control the rate of speed, direction, flow, mass, shape and the pressure of the stream that emerges from the nozzles themselves.
Now, given that they have a wide range of applications, have you ever wondered how the pump knows when and how to shut itself off when you fill the car with gas? Thus, the nozzle. Grenville Sutcliffe, the Husky Corporation President, has taken it upon himself to explain how gasoline fueling nozzles operate. He mentions many of the safety features that are being built into fueling nozzles as well. Check it out!