Generally, the term "giblets" refers to the heart, liver and gizzard of domesticated fowl and game birds. Sometimes the neck is also included in this grouping. All but the liver are used for flavoring stocks and soups. The liver is usually cooked separately and, in the case of ducks and geese, is considered a delicacy.
From The Food Lover's Companion, Fourth edition by Sharon Tyler Herbst and Ron Herbst. Copyright © 2007, 2001, 1995, 1990 by Barron's Educational Series, Inc.