All real solid surfaces are, to some extent, heterogeneous. This book provides a detailed survey of the present state of gas adsorption andcoverage extends from basic principles to computer simulation of adsorption. Underlying concepts are clarified, and the strengths and weaknesses of the various methods are examined. Topics discussed include adsorption isotherm equations for different types ofheterogeneous solid surfaces, studies of the phase behaviour of gasesabsorbed, the methods for determining the nature of surface heterogeneity and porosity from experimental data, and computersimulation of adsorption on these surfaces. The text is intended for graduate students and professionals in physical chemistry, and forchemical engineers working on catalysis and gas separation.