Transparent conducting oxide (TCO) materials have unique electrical and optical features. One of many TCOs widely employed in practical optoelectronic devices is indium tin oxide (ITO). Many characterization techniques are used to study materials' nonlinear optical (NLO) properties. The simplest and most accurate technique among these is the Z-scan technique, which is widely used. This article introduces a comprehensive review of the optical nonlinearity of the interaction of a high-intensity laser source with an ITO semiconductor material as a promising material for NLO applications.