Quantifying microstructural parameters has received considerable attention and success in developing procedures and using such data to develop structure/property relationships has been achieved. This article reviews many of the simple stereological counting measurements of volume fraction, grain structure (two-phase grain structures, and nonequiaxed grain structures), grain size, and inclusion content. It also reviews simple relationships between number of grains per unit area, number of intersections of a line of known length with particle or grain, and number of interceptions of particles or grains by a line of known length.