These notes are devoted to the analysis on a capacity space, with capacities as substitutes of measures in the study of function spaces. The goal is to extend to the associated function lattices some aspects of the theory of Banach function spaces, to show how the general theory can be applied to classical function spaces such as Lorentz spaces, and to complete the real interpolation theory for these spaces included in Cerdà (J Math Anal Appl 304:269-295, 2005) and Cerdà et al. (AMS Contemp Math 445:49-55, 2007).