Flow measurement is the process of quantifying the amount of a fluid (liquid or gas) that flows through a pipe or other conduit over a given period of time. It is typically used to measure the flow rate of a fluid, which is defined as the volume of fluid passing a certain point in the system per unit of time. Flow measurement can be done using a variety of techniques, depending on the type of fluid being measured, the type of flow being measured, and the accuracy needed for the measurement.