In this article, we will discuss a very useful and important feature of Microsoft Windows 7 operating system called Saved Searches. Saved Searches (also known as Virtual Folders) can be utilized to search items matching a certain criteria, regardless of their location.
Wikipedia defines Saved Search as "Saved Search provides a means for making it easier for users to find files that are content-related." The kind of content being talked about here can range from e-mails to pictures, music to documents and more.
An improvement in Windows 7 search is its ability to find content not only by name, date, or type but also based on a bunch of other properties. For example, you want to search for all the e-mails sent by a particular person (without opening Outlook), or may be all documents on your hard drive written by a specific author, no problem! — Windows 7 has search filters to help you there.
To learn more on Windows 7 Search Filters, read Refine Windows 7 search results using filters.
What makes Windows 7 search filters interesting is when the search is persisted to disk. When a search is saved, instead of saving the actual search results, Windows 7 saves only the criteria parameters used to perform the search. Let's say you use the following query to search for all of the emails sent by john.doe@example.com:
kind:=email from:=john.doe@example.com
Now, when you save this search and come back to the results later, Windows 7 would perform the search again bringing you up-to-date results. The only difference is that because you already had specified the criteria when you saved the search, you don't need to provide it again. Windows 7 will use the same criteria to bring up the latest results.
To perform and save a search, hold down the Windows Logo key, press F once and then, release the Windows Logo key. On the upper-right hand corner of the window, you'd see a search box. Type your search query in that box and then, click Save search in the horizontal tool strip just below the search box. Choose a name you want to give your saved search and click Save.

Note: As soon as you save the search, it will show up under the Favorites group in Windows Explorer by default.
Saved searches were earlier called Virtual Folders because they worked and behaved just like the regular folders when they actually were not. Whenever a virtual folder is accessed, the search is run and the results are presented as if a regular folder is being shown.
The term "Virtual Folder" was dropped later in favor of Saved Search. The word folder in Virtual Folder did not make any sense because regular folders contain files. However, virtual folders cannot contain any type of item inside them. Moreover, physically a virtual folder is just a file storing a search query.