AgGaS2, commonly abbreviated as AGS, is a ternary chalcogenide compound that has gained considerable attention for its nonlinear optical properties. This material crystallizes in a tetragonal structure and possesses a wide transparency range, extending from the visible to the mid-infrared spectrum. AGS is particularly renowned for its high nonlinear optical coefficients, which make it an attractive material for frequency conversion processes like second-harmonic generation (SHG) and difference-frequency generation (DFG). Due to these attributes, AGS has been utilized in a range of optoelectronic applications, including optical parametric oscillators and tunable infrared lasers. Its nonlinear optical performance is highly anisotropic, meaning that the material's properties can vary depending on the crystallographic orientation, a factor that must be considered in device design and fabrication. Like many chalcogenides, AGS is sensitive to thermal and mechanical stress, requiring careful handling and environmental control. Overall, AgGaS2 serves as a critical material in the realm of nonlinear optics, offering a unique combination of wide transparency and high nonlinear coefficients that continue to make it a subject of ongoing research and technological development.