Whole grains are cereal grains that retain the bran and germ as well as the endosperm, in contrast to refined grains, which retain only the endosperm. Whole-meal products are made from whole-grain flour.
Common whole-grain products include oatmeal, popcorn, brown rice, whole-wheat flour, sprouted grains, and whole-wheat bread. Common refined-grain products include white rice, white bread, hominy, and pasta (although whole-grain varieties of pasta are available).
Whole-grain products can be identified by the ingredient list. Typically, if the ingredient lists "whole wheat," "wholemeal," or "whole corn" as the first ingredient, the product is a whole-grain food item. Whereas, terms such as "enriched" and "bromated," among others, could indicate that the food lacks whole grain.
"Wheat flour" (as opposed to "whole-grain wheat flour" or "whole-wheat flour") as the first ingredient is not a clear indicator of the product's whole grain content. If two ingredients are listed as grain products but only the second is listed as whole grain, the entire product may contain between 1% and 49% whole grain. Many breads are colored brown (often with molasses) and made to look like whole grain, but are not. In addition, some food manufacturers make foods with whole-grain ingredients, but, because whole-grain ingredients are not the dominant ingredient, they are not whole-grain products. Contrary to popular belief, fiber is not indicative of whole-grains. The amount of fiber varies from grain to grain, and some products may have things like bran, peas, or other foods added to boost the fiber content. 
Other misleading descriptions include:
“contains whole grain”
“made with whole wheat”
These do not correspond to any government standards (see below) and thus imply nothing about the product's nutritional makeup.
In Canada, it is legal to advertise any food product as "whole wheat" with up to 70% of the germ removed. While the resulting product will contain the benefit of fiber in the nutritional information, it lacks the more recently-discovered health benefits of anti-oxidants found in the wheat germ. Canadian consumers can be assured of whole-grain products by a label stating 100% whole wheat.
Whole grains are often more expensive than refined grains because their higher oil content is susceptible to rancidification, complicating processing, storage, and transport.
Similar to the distinction between whole and refined grains is that between whole pulses and refined dal.
From AACC (American Association of Cereal Chemists) definition: "Whole grains shall consist of the intact, ground, cracked or flaked caryopsis, whose principal anatomical components - the starchy endosperm, germ and bran - are present in the same relative proportions as they exist in the intact caryopsis.”
U.S. Standards of Identity
The following names indicate whole-grain products, in accordance with the federal government:  
“whole wheat bread”
“whole wheat rolls”
“whole wheat buns”
“whole wheat macaroni”
“whole wheat spaghetti”
“whole wheat vermicelli”
“Cracked wheat” (as an ingredient, not part of a name, as in "cracked wheat bread")
“Whole wheat flour”
“Graham flour” (as an ingredient, not as part of a name as in “graham crackers”)
“Entire wheat flour”
“Bromated whole wheat flour”
“Whole durum flour”
“bulgur (cracked wheat)” (note that "bulgur" by itself may or may not indicate whole grain)
Whole grains are believed to be nutritionally superior to refined grains, richer in dietary fiber, antioxidants, protein (however lacking in the amino acid lysine), dietary minerals (including magnesium, manganese, phosphorus, and selenium), and vitamins (including niacin, vitamin B6, and vitamin E). Manufacturers are sometimes required by law to fortify refined grain products to make up for the loss of vitamins and minerals.
The greater amount of dietary fiber, as much as four times that found in refined grains, is likely the most important benefit, as it has been shown to reduce the incidence of some forms of cancer, digestive system diseases, gum disease, coronary heart disease, diabetes, and obesity. Some of these protective effects occur because carbohydrates from whole grains are digested and enter the bloodstream more slowly (as measured by the glycemic index). Many health studies have shown that whole grains have numerous cardiovascular benefits.
Some store-bought grains can be germinated and sprouted for additional nutritional benefits.
One of the first in the western hemisphere to endorse and encourage the eating of whole grains instead of refined grains was Dr. Thomas Allinson, a British physician.
When searching for whole-grain foods, it is important to note that any products made with flour can have the same effect on blood sugar, whether the flour is produced from whole grains or not. For example, whole-grain wheat bread and white bread can have the same glycemic index. Grinding grains into flour increases the surface area upon which enzymes work to more quickly convert starch into glucose. Keeping grains as close to their original form as possible slows or prevents the digestion of starch, and a slower digestion is responsible for preventing spikes in blood sugar (which over time may lead to insulin resistance).