This book explores the principles, methods, and applications of crystallization, focusing on coordination complexes. It covers nucleation, crystal growth, and factors like supersaturation, temperature, and concentration. Various crystallization techniques, including slow evaporation, vapor diffusion, and seeding, are discussed alongside advanced computational approaches like molecular dynamics (MD) and density functional theory (DFT). Characterization methods such as X-ray crystallography, spectroscopy, and thermal analysis are examined, highlighting their role in drug development, catalysis, materials science, and biological systems. The book also addresses challenges in crystallization, offering solutions and discussing the role of chromatography in obtaining high-purity crystals. Combining experimental, theoretical, and computational insights, this book is an essential resource for researchers optimizing crystallization processes.