Wave interference and photon tunneling can result in significant enhancement of the radiative transfer for closely spaced objects. Nanoscale thermal radiation holds promise in near-field thermophotovoltaic devices, nanomanufacturing, and advanced thermal management. An overview of recent development in nanoscale thermal radiation will be given with an emphasis on engineering applications. The fundamental of near-field thermal radiation will be present along with the predicted results for various materials. The maximum achievable near-field heat transfer between two parallel plates is predicted. Unlike far-field radiation, the penetration depth in nanoscale radiation depends on the vacuum gap in addition to material properties. Consequently, a 10 nm SiC film can become essentially opaque when the vacuum-gap width is less than 10 nm. In addition to the calculation of near-field energy transfer between the two media, it is important to understand the direction of energy flow between them. The the energy streamline method is developed to trace the direction of energy flow, inside the emitter, receiver, and the vacuum gap. The results obtained from this research will facilitate the future design of MEMS devices and applications of nanoscale radiation for energy harvesting.