Heat flux or thermal flux is the rate of heat energy transfer through a given surface. In this book, the authors present topical research in the study of the processes, measurement techniques and applications of heat flux. Topics discussed include measuring heat flux and heat transfer coefficients; the science and application of heat flux biocalorimetry; measuring the thermal conductivity and the heat flux of soil as a function of air pressure; the net heat flux in the Mediterranean Sea; simulation of heat flux transport in the edge plasma of small size diverter tokamak and meridional heat fluxes in the North Indian Ocean.