Understanding energy transfer via near-field thermal radiation is critical for the future advances of nanotechnology. Evanescent waves and photon tunneling are responsible for the near-field energy transfer being several orders of magnitude greater than that between two blackbodies. The enhanced energy transfer may be used for improving the performance of energy conversion devices, developing novel nanofabrication techniques, and imaging nanostructures with higher spatial resolution. Near-field heat transfer can be analyzed using fluctuational electrodynamics. This article reviews the fundamentals of near-field radiation and outlines the recent advances in this field. Important results are presented for near-field energy transfer between parallel plates and between multilayered structures. Application of near-field thermal radiation in near-field thermophotovoltaic devices is also discussed. Copyright © 2009 John Wiley & Sons, Ltd.