It's very hard for me to explain this but I'll try... When I open a commercial beer bottle (or quality homebrew) and I put my nose next to the opening, there's always a good and pleasant aroma. Also, there's a pleasant "cereal" / nutty / sweet taste.
I love this taste and aroma but I don't know what within the beer makes this. Is it the malt, is it the grains, is it the hops, is it the yeast.. Any ideas?