Am confused over what is preference and application itemA Page item is the most short-lived way to store variables in session state. Page items are routinely (although not always) cleared when entering or leaving a page. They are generally used to store a value that changes most times that you enter a page. Page items are also generally intended for use primarily by code on that page. This is not to say that other pages can not or will not use them, but access from other pages has to be controlled so that they are not trying to reference a page item from a different pages after the cache for that page has been cleared.
Where will we use preference as a source type.