Gather chicken bones, skin, and any leftover meat
Place chicken pieces in a large pot
Add cold water to cover the chicken
Add onions, carrots, celery, and garlic if desired
Add salt, pepper, and herbs if desired
Bring to a boil
Reduce to a low simmer
Skim off any foam from the surface
Simmer for 2 to 4 hours
Add more water if needed to keep ingredients covered
Strain the stock through a fine sieve
Discard the solids
Cool the stock quickly
Refrigerate or freeze the stock