In recent years, as per global forecasts, heat transfer enhancement is legion. In response, "nanofluid" is ranked first in the top echelons of researches, especially in the prestigious institutions worldwide in this field. You get an overview of studies and applications of nanofluids. However, to obtain a deep understanding of this text, the authors kindly propose that readers to have an adequate background of the nanofluid field. Next, this book presents a unified conception of a new typical nanofluid called "Hybrid nanofluid" that is a combination of two types of nanoparticles dispersed simultaneously in a base fluid. Accordingly, it has a superior exclusivity compared to the common nanofluid today. The emphasis throughout the book is on the thermal and hydrodynamic performance of hybrid nanofluid compared to that of nanofluid and also a conventional one. The book endeavors to attract a great deal of interest by employing text, pictures, graphs, and definitions to illustrate points and highlight concepts.