Phase-change processes, such as pool and flow boiling, are generally very effective modes of heat transfer. However, the demands of modern thermal systems have required the development of methods to enhance boiling systems. While heat fluxes above 108W/m2 have been accommodated in carefully controlled situations, the required fluid and the convective conditions usually dictate maximum heat fluxes several orders of magnitude lower. Two major contemporary areas, enhanced surfaces for pool boiling and enhanced surfaces and inserts for forced convection boiling/vaporization, are discussed, as they facilitate the attainment of high heat fluxes. In addition to these passive techniques, active techniques and compound techniques are mentioned. The taxonomy of enhanced heat transfer is covered, and recommendations are given for future work.