This "bone broth" you’re going to make is actually "beef stock." "Beef broth" is made with both meat and bones and simmered on high for a short amount of time. "Beef stock" is made with only bones and simmered for a long time.  So, that "stock" you buy in boxes in the food store is actually mislabeled. It isn't stock at all, but broth, because it's often made with a mix of bones and meat, it's thinner and not slowly simmered. When the world of super-foodies realized just how healthy beef stock was – which again, by definition, is slow-cooked beef bones – they wanted to delineate between the standard, store-bought, intensely boiled, quickly made (and mislabeled) “stock” that you buy in stores. So this bunch of folks essentially branded true "beef stock" as “bone broth” since it’s a term that was not commonly used for store-bought (mislabeled) beef "stock." Quite confusing. This recipe is not for over-salted, heat-blasted, preservative-filled beef stock, however. It’s for utterly nutritious, extra fancy (and technically mislabeled) “bone broth.”