The Brussels (or brussels or brussel) sprout (Brassica oleracea Gemmifera Group) of the Brassicaceae family, is a cultivar group of Wild Cabbage cultivated for its small (typically 2.5 - 4cm, 1 - 1.5 inches diameter) leafy green buds, which resemble miniature cabbages. The name stems from the original place of cultivation, not because of the vegetable's popularity in Brussels.
This entry could also be a "trendy", considering how hot the vegetable seems to be these days. For years and years, I heard only a little about Brussels sprouts and, even then, much of what I did hear was negative. I felt the same way. My mom's always loved them, but when she cooked Brussels sprouts when I was a kid, they were, well, terrible - frozen then steamed and just sort of gross.
But for whatever reason, the oft-maligned veggie is enjoying a fabulous renaissance. Fortunate for me, too, as I've discovered that I love them. Not frozen, and not steamed, but how good are roasted Brussels sprouts? Or sauteed with a little bacon?
Really, really. That's how good they are.