Saha, Debjani2026-10-072026-10-072022http://nits.ndl.gov.in/handle/123456789/169For a pretty long time, man has appreciated crystals and cherished their beauty. Mother Earth's gifts of gems and crystals have long piqued human interest, and belief in the healing properties of jewels and minerals stretches back at least two thousand years. The use of stones as ornaments appears to have been practised from the dawn of time. Crystals are now the foundations of modern technology. There would be no electronics industry, no photonics industry, no fibre-optic communications, very little contemporary optical equipment, and some significant production engineering gaps without crystals. There has been a rising interest in crystal formation processes in recent decades, especially in light of the increasing demand for materials for technological applications. So it is very important for us to know about crystals and their application. Keeping it in my, in this paper, an overview of crystal growth, synthesis, and a brief description over some of the important characteristics of a single crystal named Dimethyl amino pyridinium 4-nitrophenolate 4-nitrophenol are given. While studying its characterization we will also encounter the importance of NLO in today’s world and possibilities for tomorrow. By doing second harmonic studies, it will be shown here that the sample single crystal shows nonlinear optical properties.enThesis