Needs are basic human requirements, which include the basics needs of food, shelter and clothing. On the other hand, wants are the ways in which needs are satisfied. For instance, the need of food is satisfied by the wants of different types of food, depending on cultural and socioeconomic factors.
Index fossils (also known as guide fossils, indicator fossils or zone fossils) are fossils used to define and identify geologic periods (or faunal stages).
