This book outlines the evolution of molecular spectroscopy in the condensed phase. Covering an exceptional breadth of classical and novel spectroscopies — including far-ultraviolet, ultraviolet, near-infrared, infrared, far-infrared/terahertz, and new Raman modalities — the text presents a comparative analysis of the characteristics and advantages of each technique. Beyond instrumentation, special attention is given to recent breakthroughs in spectral analysis methods such as quantum chemical calculations and chemometrics which have transformed data interpretation. Real-world case studies span life sciences, biomedical research, polymers, and nanomaterials, demonstrating spectroscopy's pivotal role in contemporary science and engineering. Interwoven throughout are landmark studies from the author's group, whose five decades of pioneering research have shaped the global field of molecular spectroscopy.