This paper reviews current publications and the concept of the intelligent reflecting surface (IRS) in future wireless networks. The unpredictable fading of wireless channels has become one of the most significant performance bottlenecks. The IRS consists of many metasurface devices that may be individually adjudicated to add phase changes to signal reflec- tions. It may actively alter the signal propagation parameters in favor of signal reception and achieve the idea of a smart radio environment. In this survey, we first introduce essential concepts of the IRS and the realizations of its configurability. Then, we discuss the joint optimization of the IRS’s phase control and the transceivers’ transmission control in different network design problems, e.g., capacity maximization and energy minimization problems; beamforming discussion of IRS-assisted wireless net- works, and using the deep learning method for discussion in IRS. Finally, we highlight some interesting practical challenges, such as security transmission, unmanned aerial vehicles (UAVs), and mm-Wave communication.