Couscous bought packaged in supermarkets is not a grain in itself. It is made from semolina, a coarsely ground durum wheat. Some couscous dishes however, are made from entire grains, such as barley, millet and corn.
A staple in most North African countries, it is usually served as the centrepiece of a meal that is accompanied by a moist dish, most notably a tagine. The name is derived from the cooking utensil traditionally used for its preparation, the couscousière, a double layered brass or copper pot that braises the tagine on the bottom and steams the couscous on the top. Information on when couscous was first made is scant, but Charles Perry from the Los Angeles Times believes it was around the eleventh or twelfth century.
Every packet couscous I have seen gives instructions to pour boiling liquid, either water or stock, directly onto the couscous. As shown by the couscousière, steaming is the traditional method. It allows the semolina to expand to its full fluffy size, providing a culinary delight rather than gut luggage. Couscousières are rather expensive and let's face it, it hardly has multiple uses in the kitchen, so here is a method using just a pot and a colander;
Place the desired amount of couscous (it will treble in volume once cooked) into a sieve and rinse under cold running water. Set aside for a few minutes and let some moisture absorb. Pour a good slug of olive oil into the palm of your hand and toss the now clumped couscous around and coat the granules in oil. Pour the couscous into a colander and set over a pot of simmering water. If your colander and pot don't make a tight fit, use a moist tea-towel to seal the gap. There is no need to cover the couscous. Once the first whisps of steam emerge from the surface of the couscous, steam for 15 minutes. Remove from the heat and dump into a bowl. Once cool enough repeat the oiled hands procedure, this time adding some sea salt. (This, as they say, can be done in advance). Put the couscous back into the colander and steam for another 15 minutes. Turn out again into a bowl, this time add a large knob of butter and check again for salt. Ready to go.
All packet couscous has been partially cooked, so the only way to get raw couscous is to make it yourself. If you are keen, it isn't that hard, and I have a © recipe that I will send you if you ask politely.