Back in the old country, Corned beef and cabbage was a traditional Easter Sunday dinner in the more rural parts of Ireland. Corning is a method of preserving meat that has nothing to do with corn. The word actually comes form an Anglo-Saxon term referring to the "corns," or large pellets of salt that were rubbed into the meat during the curing process. In the days before the industrial revolution and modern refrigeration, curing of meats with salts and spices was the only way for the lower and middle classes to preserve meats, as they rarely had access to fresh meat.
In the days since then, refrigeration and freezing have become more accepted and less time weary methods of preserving food. Corned beef is still very popular in the United States as a feast meal on St. Patrick's day, as a nostalgic link to the old ways. Although the dry salt rub has been replaced by a salt-water brine method, the term corning has remained as it just simply sounds more apealling than Brined or Pickled Beef. Ironically, since the introduction of refrigeration it's more popular in the USA than in Ireland, as the trend there has been to eat fresh meats.
Because of its roots as peasant food, corned beef is often made from many of the less tender cuts of beef such as the brisket, rump or round. Preparation then, often requires long, moist, cooking to bring the meat to a palatable tenderness. This, among other reasons is why so much fat is left on the cut. After cooking the meat may still appear red or pink throughout, and is not an indication of rareness. Nitrate is used in the curing process and this chemical will stabilize the color of the meat. When the cooking is completed, let the meat stand for ten minutes before carving, this will allow the meat to absorb its juices and make it easier to cut. When you cut it, make the slices thin and cut across the grain of the meat. Doing so will make it much easier to chew.
As an aside, a completely cooked, properly spiced and smoked corned beef brisket results in pastrami. | 
