The ever-increasing use of harmonic causing loads in the power system has led to the aggravation of many power quality issues mainly harmonics. The distortions triggered by these power quality issues must comply with the limits set by the international standard organizations. The mitigation of these problems is imperative and active power filters/active power quality conditioners are a practical solution to these issues. The control strategy plays a very significant role in the effective functioning of the APF. The control strategy also determines the performance, efficiency, stability, and reliability of the APF. This paper proposes a comprehensive review on the state-of-art control technologies of active filters highlighting their main features. Various control strategies are studied and investigated based on their characteristics, performance, applicability, and implementation. © 2018 IEEE.