Grits, polenta, and cornmeal all come from dried kernels of corn that have been ground into one of three textures—coarse, medium, or fine. When the corn is ground, the coarser particles become grits, while finer granules are used for polenta. The most finely ground corn becomes cornmeal, and even cornmeal has varying textures, from coarsely ground to finely ground (also called corn flour).
Stone-ground grits, our choice for most grits recipes, have a chunkier texture and a more "corny" flavor than the quick grits sold in most grocery stores. Stone-ground grits take longer to cook than quick grits. They also require more stirring to release the starch and soften the grains, but stone-ground grits are certainly worth the effort.