It's pretty tough to find whole barley outside of health food stores and even the most "whole" version will be missing its hull. This "hulled barley" has still got much more fiber and minerals than pearled barley which has been stripped of the germ and the bran and polished up to six times to give it a smooth surface. Over half of the barley grown in the US is used for beer and nearly all of the rest is used for livestock, although this is a truly delicious and nutritious grain.
Hulled barley can be stored in the fridge in an airtight container or at least kept away from light, heat, and moisture-it will stay fresh for up to several months. Pearled barley can be kept at room temperature for a longer time since most of the oils which could go rancid have already been removed.
Substitute hulled barley for any recipe where you see pearled barley, but keep in mind that it will take closer to two hours to cook, much longer than the 45 minutes recommended for pearled. You might want to cook it in a separate pot and add it into recipes at the end, so your other cooking times don't change. You can also serve it on its own with simple seasoning as a side dish or in grain salads.