A formal culture region is an area inhabited by people who have one or more cultural traits in common, such as language, religion, or system of livelihood. It is an area relatively homogeneous with regard to one or more cultural traits. The geographer who identifies a formal culture region must locate cultural borders. Because cultures overlap and mix, such boundaries are rarely sharp even if only one cultural trait is mapped and so there are cultural border zones, rather than lines. The zones broaden with each additional cultural trait that is considered because no two traits have the same spatial distribution. As a result, instead of having clear borders, formal culture regions reveal a center or core, where the defining traits are all present. Away from the central core, the characteristics weaken and disappear. Thus, many formal culture regions display a core-periphery.