ABSTRACT
Abstract Understanding, measuring, and interpreting equilibrium contact angles appear to be simple, but may actually be quite confusing. This paper is an attempt at a guide to the perplexed. First, a comprehensive, clearly defined terminology is suggested. Then, the theory of equilibrium contact angles on smooth, rough, or chemically heterogeneous surfaces is briefly discussed. Finally, the practical implications of the theory to contact angle measurement and interpretation are indicated and explained.
