Is couscous a grain or a pasta? Neither, really. A Middle Eastern and North African staple, couscous is simply durum semolina (the wheat flour from which most Italian pastas are made) that has been lightly moistened with salted water and rolled into little granules. Medium-grain (also called Moroccan) couscous is widely available in the U.S., but it's hardly the only option. At Middle Eastern groceries, you'll see varieties as fine as sand and as large as baby peas.
Traditionally, couscous is steamed in a couscoussière over broth or water and served with butter or with stewed vegetables or meats. But many recipes suggest simply mixing couscous into boiling liquid and setting it aside to swell and soften. Although this method sacrifices a certain degree of fluffiness for convenience, it does work quite well for medium and fine couscous. Larger-grained versions can be steamed in a couscoussière or simmered in broth or water until tender.
Store couscous in sealed containers or bags to keep out moisture. At room temperature or cooler, it will keep well for a year.