Sometimes depending on your requirements, you need to create site collections with specific urls beyond the typical http://server/sites/sitename.
Maybe you want to create a url such as http://server/projects/sitename or http://server/teams/sitename.
To do this, you need to go to the SharePoint Central Administration page for Windows SharePoint Services and select “Configure Virtual Server Settings”.
Select your site from the list.
Under the Virtual Server Management options, select “Define Managed Paths”.
At the bottom of the page, enter the path you wish to designate for your site collections. Note that the path should not already be used for something else. Keep that in mind when naming your areas.
Now when you go to a Sites Directory to create a site, your new option will be available for you when you create the url.