In this paper presents a compilation of all the principles of level measurement of liquids and solids that can be found at industrial level is performed. As a first step, some key definitions in the instrumentation level are shown, as are: measurement system, indicating instrument, sensor and transmitter. Then it is disclosed that is the measurement point level and continuous level measurement, based on the fact that there are two ways of measuring distinct level governing the operation of the meter. As with any type of instrumentation, measurement units and pressure level are shown, the latter to the level meters that take advantage of the hydrostatic pressure from the liquid. the basic parts, the physical phenomena and, in some cases, the equations governing the behavior meter: Finally, the operation of each of the level measuring principles, revealing described.