An alias is a mechanism for mapping a physical path to a logical web server path. Aliases are usually used as a way of accessing content outside the web root.
For example, each site maps "/" to its web root.
If you have a directory called "c:\documents" that you want to make available to the web server. You can create an alias called "/documents" that maps to "c:\documents" and the URL to get there will be "http://myserver/documents/".
You can add a new alias by clicking on "Add Alias" from the Aliases section of a website.
To edit an alias, click either the "Virtual Path" link or the edit icon.
The virtual path is the part of the URL after the domain used for navigating the aliased folder.
Specifies the physical path on the server or network. Its contents will be served when a user navigates to the virtual path.
Each website must contain at least one alias for the web root ("/"). The root of the website is the folder that contains the documents that are to be displayed when a user accesses the website without specifying a folder, for example:
http://www.mysite.com/index.html
Perceptive Enterprise Search will look in the folder aliased to "/" for the file "index.html", if an alias for "/" does not exist, your users will receive a "404 - Not Found".