Before revision:  This didactic text provides a brief review of some of the approaches that have been used to characterize complexity, and also suggests a possible definition of complexity based on the cost assigned to mapping the entity of interest, as well as on the  cost of the error implied by its respective reconstruction .
After revision:  This didactic text provides a brief review of some of the approaches that have been used to characterize complexity, and also suggests a possible definition of complexity based on the cost assigned to mapping the entity of interest, as well as on the cost of developing a model, plus the cost of its respective operation. The proposal is illustrated respectively to several applications examples, including a real-data base situation .