A level is a measuring instrument used to determine the horizontality or verticality of an element. There are different types and they are used by surveyors, carpenters, bricklayers, blacksmiths, aluminum workers, photographers and others. A level is a very useful instrument for construction in general and even for placing a painting, since perspective generates errors.

The spirit level was an invention of the French physicist and writer Melchisédech Thévenot, in 1661 or 1662.

The principle of this instrument is a small transparent tube (glass or plastic), which is filled with liquid (alcohol or ether) with an air bubble inside. If the bubble lies symmetrically between the two marks, the instrument indicates an exact level (for practical purposes) which may be horizontal, vertical or other, depending on the general position of the reference-only measuring instrument.

The topographic level is an instrument used in topography and surveying that, analogous to a theodolite, allows you to measure levels and perform leveling with high precision using a wooden mason and a plastic tube.

A reed level is an Arab invention for determining level for construction purposes. A hole is placed through a long, straight reed and water is poured into the center. When the flow from both sides is equal, the reed is level. The device serves the same purpose as a spirit level.

Archipendulum or plumb level, also called mason's level, was an ancient level. The base of the wooden triangle of these plumb levels sat on a surface, and the plumb line marked the "weight" or horizontal levelness of the plane on which it sat.

The chorobate was a ruler in which a slot was drilled that the surveyor filled with water. At each end of the ruler, a plumb line allowed the vertical to be checked. By checking the level of the upper plane of the water in the groove of the chorobate ruler, the inclination of the surface that was being measured could be determined through the scale that the chorobate had at each end. Through this observation, it was possible to deduce the inclination that must be given to the aqueduct to guarantee the same inclination in the work.

The chorobate was equipped with 2 viewers at each end of the ruler. The space between the two scopes defined the precision of the measurement; The rules generally had a length of 20 feet, or about 6 meters. When the wind did not allow the use of plumb lines for adjustment, the upper slot that was filled with water was used to define the level of the device.