This Brief deals with Performance Evaluation Criteria (PEC) for heat exchangers, single phase flow, objective function and constraints, algebraic formulation, constant flow rate, fixed flow area, thermal resistance, heat exchanger effectiveness, relations for St and f, finned tube banks, variations of PEC, reduced exchanger flow rate, exergy based PEC, PEC for two-phase heat exchangers, work consuming, work producing and heat actuated systems. The authors explain Performance Criteria of Enhanced Heat Transfer Surfaces—the ratio of enhanced performance to the basic performance—and its importance for Heat Transfer Enhancement and efficient thermal management in devices.