Spin orbit torque (SOT) has been proposed as a potential alternative mechanism to the conventional spin transfer torque (STT) for the magnetization switching. Recently, theoretical and experimental works revealed the novel factors influencing the SOT-driven magnetization switching. Emerging SOT-based spintronics memories and circuits were explored to implement fast and energy-efficient write operation. However, the perspective of the SOT mechanism is still challenged by some serious shortcomings, such as area penalty, relatively large switching current density and undesirable use of external magnetic field. Here, we review the progresses in the SOT mechanism involving the magnetization dynamics, device design and circuit development. Key issues to be addressed in optimizing the SOT devices are pointed out. In particular, we discuss the potential solutions to develop high-density SOT-based memories and circuits.