Multiple research articles fabricate large electronic devices (with lateral sized 大于10 µm2) and claim that the behaviors observed are “promising” for applications like data storage or computing. Such claims are highly misleading because those technologies employ ultra-scaled electronic devices (e.g., transistors, memristors) with lateral sizes 小于0.01 µm2. In small-size devices, the number of local defects in the materials can be remarkably different, which almost always affects switching voltages, energies and times, as well as state resistances may be remarkably different than in larger devices, which also affects yield, variability and reliability. Hence, the fact that a large device (大于10 µm2) shows whatever performance does not imply that a small device (小于0.01 µm2) with identical materials composition will also exhibit it. In this seminar, I will show multiple methods to characterize the electronic properties of different materials and devices at the nanoscale. I will describe some of the properties I have analyzed in metal-oxides, graphene, molybdenum disulfide, hexagonal boron nitride, and nanowires. I will describe the setups that I have developed in order to carry out these studies, with special emphasis in conductive atomic force microscopy. The main properties that I will discuss are related to leakage current, dielectric breakdown and resistive switching in thin dielectrics, as well as piezoelectricity in two-dimensional materials and nanowires.