Overview
Windows uses the concept of special folders to present the contents of the storage devices connected to the computer in a fairly consistent way that frees the user from having to deal with absolute file paths, which can (and often do) change between operating system versions, and even individual installations. The idea has evolved over time, with new special folders being added in every version of Windows since their introduction in Windows 95.
Microsoft's "Compatible with Windows" software logo requires that an application make use of special folders locations to locate the appropriate folders in which documents and application settings should be stored.
A special folder can either be a reference to a physical file system directory, or a reference to a "virtual" folder. In the former case, they are analogous to environment variables — in fact, many of the environment variables that are set in a user's session are defined by where the special folders are set to point to.
Virtual folders, however, do not actually exist on the file system; they are instead presented through Windows Explorer as a tree of folders that the user can navigate. This is known as the Shell namespace. On Windows XP systems, the root of this namespace is the Desktop virtual folder, which contains the My Documents, My Computer, My Network Places (Network Neighborhood in Windows 95 and 98) and Recycle Bin virtual folders. Some virtual folders (like Desktop) have an accompanying special folder that is a reference to a directory on the physical file system. Windows Explorer displays the combined contents of a virtual folder and its associated file system folder to the user. This can be seen in Figure 1, which shows the Folder view in Windows XP's Explorer; in the Desktop virtual folder, the four standard virtual folders can be seen, as well as an additional folder, "a folder on the desktop", which is a real folder located in the Desktop directory in the user's profile.
Some third-party programs add their own virtual folders to Windows Explorer.
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