Virtual Directory is a directory that appears to Web browser users as a subdirectory of a Web site’s home directory but in fact might be located in a different folder, drive, or server. Virtual directories are supported by Internet Information Server (IIS) in Microsoft Windows NT and Internet Information Services (IIS) in Microsoft Windows 2000.
For example, consider a user accessing a Web site by using the following Uniform Resource Locator (URL):
The directory otherstuff appears to the user to be a real subdirectory of the home directory www.microsoft.com, while in fact it could be a virtual directory that is mapped to a share on a different server on the Web provider’s network.
The advantage of using virtual directories is that content does not need to be stored only on the Web server - it can be distributed on other servers throughout the Web provider’s network. These servers can be located at secure, strategic locations for easy access by Web content developers. The disadvantage is a slight performance hit due to data being transmitted over the network.