Intelligent Reflecting Surfaces (IRS), is an emerging technology in wireless communications due to the spectral and power efficiency they tout. These are structures that are composed of multiple antenna patches that can actively or passively control the redirection of electromagnetic waves incident on them, changing phase and amplitude as per use. This causes them to see the use in various wireless communication systems, where they can Substantiate and improve upon existing multiplexing techniques. This paper presents a review of the developments in these applications and goes on to present a systematic review of the results that they have yielded.