For a general characterization of particles, there is no single instrument that is the “right tool for every job”. In fact, more than 400 different techniques exist for particle counting, sizing, analyzing, and characterizing. Typically, instrumentation is chosen by engineers and researchers through consideration of what measurements need to be made, and in what environment the measurements need to be made. There are two primary considerations for selecting instrumentation: a) single particle versus ensemble, and b) the environment. The measurement is made in air, liquid or vacuum. In general, morphological information such as shape and aspect ratio, as well as surface information, such as texture and roughness parameters, cannot be obtained using ensemble techniques.