A load cell is a type of force sensor that, when connected to appropriate electronics, return a signal proportional to the mechanical force applied to the system. They can be hydraulic, pneumatic, or, most commonly, based on strain gauges.
A load cell is a transducer which converts force into a measurable electrical output. Although there are many varieties of load cells, strain gage based load cells are the most commonly used type.
Load cell designs can be distinguished according to the type of output signal generated (pneumatic, hydraulic, electric) or according to the way they detect weight (bending, shear, compression, tension, etc.)