Nanogap electrodes (namely, a pair of electrodes with a nanometer gap) are fundamental building blocks for the fabrication of nanometer-sized devices and circuits. They are also important tools for the examination of material properties at the nanometer scale, even at the molecular scale. In this review, the techniques for the fabrication of nanogap electrodes, the preparation of assembled devices based on the nanogap electrodes, and the potential application of these nanodevices for analysis of material properties are introduced. The history, the research status, and the prospects of nanogap electrodes are also discussed.