Windows Explorer includes significant changes from previous versions of Windows such as improved filtering, sorting, grouping and stacking. Combined with integrated desktop search, Windows Explorer allows users to find and organize their files in new ways, such as stacks. The new Stacks viewing mode groups files according to the criterion specified by the user. Stacks can be clicked to filter the files shown in Windows Explorer. There is also the ability to save searches as virtual folders or search folders. A search folder is simply an XML file, which stores the query in a form that can be used by the Windows search subsystem. When accessed, the search is executed and the results are aggregated and presented as a virtual folder. Windows Vista includes six search folders by default: recent documents, recent e-mail, recent music, recent pictures and videos, recent changed, and "Shared by Me". When sorting items, the sort order no longer remains consistently Ascending or Descending. Each property has a preferred sort direction. For example, sort by date defaults to descending order, as does size. But name and type default to ascending order.