This chapter presents some of the most important currently utilized techniques for the characterization of nanostructures and nanoparticles. The techniques presented here are grouped into categories of topology, internal structure, and compositional investigation. Topological techniques presented here include field emission scanning electron microscopy (FESEM), scanning probe microscopy (SPM), and optical microscopy (confocal and NSOM), as well as particle size distribution with dynamic light scattering (DLS). Internal structure techniques presented include transmission electron microscope (TEM), magnetic resonance force microscope (MRFM), and X-ray diffraction (XRD). Compositional techniques presented include X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDS), secondary ion mass spectroscopy (SIMS), and auger electron spectroscopy (AES). To highlight the current capabilities and applications of these techniques, case studies from recent literature are presented.