1_Combine ingredients in a large pot:
Put the leftover bones and skin from a chicken carcass into a large stock pot. Add vegetables, like celery, onion, carrots, parsley. Cover with water. Add salt and pepper to taste, about a teaspoon of salt, 1/4 tsp of pepper.
2_Bring to a boil and reduce to a simmer:
Bring to a boil and immediately reduce heat to bring the stock to barely a simmer. Simmer partially covered at least 4 hours, occasionally skimming off any foam that comes to the surface.
3_Concentrate the stock (optional):
If making stock for future use, you may want to reduce the stock by simmering an hour or two longer to make it more concentrated and easier to store.
4_Strain the stock:
Remove the bones and vegetables with a slotted spoon or spider ladle, and strain the stock through a fine mesh sieve.