Recent advances in the understanding of adsorption, pore condensation, and hysteresis behavior in nanoporous materials have significantly improved physical adsorption characterization. Theoretical methods, such as density functional theory and molecular simulation, now allow for molecular-level descriptions of fluid behavior in pores. These methods account for surface heterogeneity and enable accurate pore size analysis across a wide range of pore sizes. Experimental techniques like gas adsorption, X-ray diffraction, and small-angle scattering have also advanced, allowing for detailed studies of complex porous systems. Gas adsorption remains the most popular method due to its ability to assess a wide range of pore sizes and its cost-effectiveness. However, accurate interpretation of adsorption data requires understanding the fundamental principles of isotherm analysis. Adsorption isotherms classify pore types based on size, with micropores (<2 nm), mesopores (2–50 nm), and macropores (>50 nm). Nitrogen is commonly used for surface area and pore size analysis, but argon and carbon dioxide are alternatives for microporosity studies. The BET method is widely used for surface area analysis, but its applicability to microporous materials is limited. The Kelvin equation is used for mesopore analysis, but it has limitations in narrow pores. The NLDFT method provides accurate pore size analysis by considering metastable adsorption isotherms and is widely used in mesoporous materials. Hysteresis in pore networks is complex and depends on pore structure and connectivity. The IUPAC classification of hysteresis loops helps in understanding pore structure. The NLDFT method is effective for pore size analysis in ordered mesoporous materials, and recent developments in QSDFT address the limitations of NLDFT in heterogeneous materials. These advancements highlight the importance of accurate pore size and surface area analysis in the characterization of nanoporous materials.Recent advances in the understanding of adsorption, pore condensation, and hysteresis behavior in nanoporous materials have significantly improved physical adsorption characterization. Theoretical methods, such as density functional theory and molecular simulation, now allow for molecular-level descriptions of fluid behavior in pores. These methods account for surface heterogeneity and enable accurate pore size analysis across a wide range of pore sizes. Experimental techniques like gas adsorption, X-ray diffraction, and small-angle scattering have also advanced, allowing for detailed studies of complex porous systems. Gas adsorption remains the most popular method due to its ability to assess a wide range of pore sizes and its cost-effectiveness. However, accurate interpretation of adsorption data requires understanding the fundamental principles of isotherm analysis. Adsorption isotherms classify pore types based on size, with micropores (<2 nm), mesopores (2–50 nm), and macropores (>50 nm). Nitrogen is commonly used for surface area and pore size analysis, but argon and carbon dioxide are alternatives for microporosity studies. The BET method is widely used for surface area analysis, but its applicability to microporous materials is limited. The Kelvin equation is used for mesopore analysis, but it has limitations in narrow pores. The NLDFT method provides accurate pore size analysis by considering metastable adsorption isotherms and is widely used in mesoporous materials. Hysteresis in pore networks is complex and depends on pore structure and connectivity. The IUPAC classification of hysteresis loops helps in understanding pore structure. The NLDFT method is effective for pore size analysis in ordered mesoporous materials, and recent developments in QSDFT address the limitations of NLDFT in heterogeneous materials. These advancements highlight the importance of accurate pore size and surface area analysis in the characterization of nanoporous materials.