Grains - What do we know?

The evolution of various models and observational techniques for detecting the physical characteristics of interstellar grains are summarized. A critical examination is given to phrases such as 'dust', the 'interstellar medium', the H II region, etc., that are routinely applied in descriptions of grains. Possible interpretations of extinction data for grains are discussed, noting the inaccuracies that are introduced by using light from a background star whose distance and spectra cannot be well characterized. The albedo of the grain wisps must be treated as an unknown, and the bases for all models must reside on the size and composition of typical grains of a given cloud. Observational targets which would permit derivation of the critical parameters for modeling the grains are briefly considered.