Book excerpt: : This book is based on research conducted on the growth and characterization of nonlinear optical crystals. Due to the significance of crystals in contemporary technology, crystal growth has been the focus of extensive research in both solid-state physics and materials science. This book serves as an introduction to the growth phenomena, specifics of growth processes, nonlinear optical phenomena, and characterization methods that are being used for the analysis. The book is divided into three chapters: The first chapter focuses on the experimental techniques of crystal growth. It outlines the several ways that crystals grow based on the phases they go through, such as solid-solid phase transition, liquid-solid phase transformation, and vapour-solid phase transformation. The optimization methods for growing high-quality single crystals are thoroughly presented. The benefits and drawbacks of methods of growth are reviewed. The second chapter explains the theory of nonlinear optical phenomena. The selection criteria for nonlinear optical materials are reviewed. The history of nonlinear optics and the various types of nonlinear optical materials are discussed. The role of amino acids in the formation of nonlinear optical crystals is well explained. The third chapter discusses characterization procedures that are essential in determining the quality of crystals. The several characterization mechanisms including the molecular structure, chemical composition, surface morphology, optical properties, dielectric properties, mechanical behavior, and thermal properties necessary for crystal analysis are described. We hope that this book will be valuable to researchers and students.