bone broth is a stock made with bones. These are often the bases of soups and sauces in classic French cooking. Generally speaking, the most common stocks are made from beef chicken veal and fish, though occasionally a pork or lamb or other specialty stock will be made. Bones in a bone broth can wither be roasted for a "brown stock" or not roasted for a "white stock".

Chicken stock is made with a chicken carcass (can be leftover from say, a roast chicken), chicken feet are outstanding for make chicken bone broth. Chicken backs (spines) are sometimes sold for chicken stock. I regularly roast a whole chicken, we eat it, save the bones, the neck and the heart and I make a stock with those. I put it one whole head of garlic (sliced in half so all the cloves are split in half) some celery, some leeks, some onions, some parsnips, a bay leaf or two, some whole peppercorns, some carrots, a sprig or two of parsley, maybe some celery root if i have some laying around, and some allspice. I like to put a bit of acid on the bones, like a small squeeze of lemon juice or some white wine because I've heard that helps extract collagen. I add a very small amount of salt, as someties you may want to reduce a stock later. Do not boil. Do not boil. Do. Not. Boil. Simmer slowly so it barely bubbles. Boiling stock makes it greasy in an unpleasant way. Skim a bit and early on and keep it cooking for at least 4 hours. Strain the liquid. Toss the spent veggies.

People roast their veggies with their bones for brown stocks (though since I am using leftovers here, I don't).

Other bones used for stocks include veal knuckles or any kind of feet/joint containing lots of collagen and gelatin. You can roast just about any bone for a stock, though some are more desirable than others. I have roasted an entire pig's skull for a stock (before I realized the farmer who gave it to me had shot it in the head and there was a bullet still in there - oops. almost had lead soup.) Sometimes the bones of more than one animal are used in the same stock, though it's best to use mostly one kind of bone.

Stock makes delicious homemade soup bases, freezes very very well and keeps almost indefinitely in the fridge if you re-boil it every 3 days or so for a few minutes.