You need bones, a large pot with a lid, water, a strainer, and (optionally) vinegar.

Do not use raw bones for stock. Roast, grill, or pan-fry the bones until they brown and begin to have black spots on them. If you use bones left over from a roast, these are already roasted and are fine to use.

Put the bones in a large pot. Cover with water and bring to a boil. Drain. Rinse the gunk off the bones and out of the pot.

Put the bones back in the pot. Cover with water. Optionally, add a splash of vinegar. Acidity technically helps to release minerals from the bones. If you use enough to be really measurable your stock will taste sour, but a splash (half a cup or less) isn’t going to hurt and might help.

Unless you are making stock for a specific purpose, there is no point in seasoning it at all. Keep it plain and then you can season it however you like, when you use it.

Cover the pot and simmer on extremely low how heat for as long as you can stand it. At least 24 hours. 72 hours would not be too long. Strain the stock into containers for storage.

We’ve found that freezing stock in glass containers, even with a lot of extra space for expansion, doesn’t work well and the glass frequently cracks. You could of course try pressure-canning in canning jars. We normally let the stock cool to room temperature and store it in freezer-safe bags. If you use this method, make sure you put the bag in a bowl or pot when defrosting. Freezer safe bags that are leak-proof when they go into the freezer have a habit of leaking when you take them out and defrost them.