This text, including the description of the most relevant phenomenologies and of some advanced techniques in heat transfer with fluids, is mainly aimed at engineers using design or computer analysis programs and codes, in order to achieve a deeper understanding of the phenomenologies and of the applied analysis methods. This text will be helpful to people engaged in developing original computer programs or design methods, because they may find in it basic information on the computer program-oriented solutions of the conservation equations and of the various flow and heat transfer mechanisms. The selection of up-to-date correlations in various heat and mass transfer branches represents, for the designers using traditional techniques, a helpful instrument to integrate the basic handbooks.The trial of representing phenomenologies and problems through elementary concepts makes this text useful to students at the graduate level involved in the study of fluid flow and heat transfer.