Corned Beef derives its name from being treated 
with large grains of coarse salt.  This allowed the meat to be preserved 
and last a long time.  Corned beef was thus a needed commodity during 
war times and long voyages, including those of related to the slave 
trade. Beginning in the 17th century, English landlords started to 
raise cattle for corn beef in much of Ireland.  This ultimately 
contributed to the Irish famine, as they pushed the natives into low 
quality lands where all they could grow was potatoes.  While Ireland 
exported much of the corned beef during the 17th to 19th centuries, it 
remained a luxury item at home, too expensive to be consumed by most of 
the population. 
Thus it was in America, where corned beef was 
relatively cheap, that the Irish re-discovered it and began consuming 
it.  Today, Corned Beef and cabbage is the standard St. Patrick's day 
meal.
Despite consuming my fair share of corned meal, I'd never cooked it.  While you can buy brisket and cure it yourself, the common way to prepare it in the US is by buying a pre-cured package of corned beef, which comes with its own little spice package, and then cooking it according to the instructions.  Boiling it for hours and finishing it in the oven it's most common, but I was lazy and decided to go for the roast-only method.  That was a mistake, as it produced a dry corned beef.  It still tasted great, fortunately. 
The mustard dressing wasn't as good as I wished.  Some recipes add brown sugar, and if I was making it again I'd add it as well.  
All in all, it was a nice meal.   I served it with potatoes O'Brien