The demand for an input to a productive process. This depends on the output of the good or service being produced. Derived demand also depends on the price of the input and the prices of other inputs which are substitutes for or complements to it. If other inputs are good substitutes, the elasticity of derived demand may be high; but if other inputs are poor substitutes, the elasticity of derived demand may be very low, especially if the input accounts for only a small proportion of total costs.