  This chapter is devoted to discussing the integration of intelligent
reflecting surfaces (IRSs), or intelligent walls, in optical wireless
communication (OWC) systems. IRS technology is a revolutionary concept that
enables communication systems to harness the surrounding environment to control
the propagation of light signals. Based on this, specific key performance
indicators could be achieved by altering the electromagnetic response of the
IRSs. In the following, we discuss the background theory and applications of
IRSs and present a case study for an IRS-assisted indoor light-fidelity (LiFi)
system. We then highlight some of the challenges related to this emerging
concept and elaborate on future research directions.
