Collections can be used as a generic way of maintaining an ordered list of stories and other items. A collection can be an alternative way of grouping a number of items to supplement the primary position in the Storymap tree.
Collections can be described with a title and description, automatically accumulating effort and value estimates for all items in the collection. But putting items in a collection does not have any functional effect on the items. Any item can be in multiple collections at the same time.