Publisher Summary This chapter presents the consolidated results obtained with controlled field emission from nanotips and in particular discusses the specific effects related to the fact that the source is atomic size. The chapter summarizes the basic results of field emission theory, including discussions of thermionic emission, to place the field emission from nanotips in the global context of electron sources. Characteristics of field emission from nanotips are also presented and discussed in the chapter. The usefulness of the very specific properties of nanotips is convincing only if they permit new advances to be developed; the chapter presents the demonstration of their utility. Among other examples, nanometric-resolved images of synthetic polymers and RNA-based biological molecules are presented and discussed. They were obtained with the Fresnel projection microscope (FPM), using the nanotip as an atom size electron source. The main features of the temperature and field dependence of the emission currents and the energy distributions of emitted electrons can be understood by considering the electrons inside the metal to be a free electron gas.