The early decades of the twentieth century saw surface science move from qualitative observations to quantitative, molecule-scale understanding of adsorption and interfacial phenomena. Research concentrated on solid–gas interfaces, developing isotherm-based methods to extract surface areas, energies, and porosity from measurements. In parallel, deposition of ultrathin films and systematic study of interfacial layers advanced molecular-scale control, enabling new materials strategies for catalysts, sensors, and electronic interfaces. A broader thread connected order, entropy, and information-like concepts to crystalline and interfacial systems, foreshadowing cross-disciplinary links between thermodynamics, information, and materials science.