Today, more people are creating multiple web sites or blogs just for themselves. They know that they would earn more if they are to maintain all these blogs. And most often these sites are all built using WordPress. But the problem with maintaining multiple sites on WordPress is having multiple folders as well for each web site install.
Another thing that makes having multiple web sites a hassle is when you are upgrading the version of your WordPress. You need to upgrade these sites individually. So if you have fifteen or more WordPress sites, then you just have to upgrade all these WordPress installs.
But now, you can make your life easier and maintain multiple WordPress sites in just one database or code base. All you have to do is tweak your wp-config.php file. In this way, you would be able to support and maintain these sites without the hassle of having multiple folders for each install. All you have to do is play with your table prefix. Once it detected the domain of the other sites, it would automatically create a brand new database or it can consider it as a reference if the domain is already programmed in the database. This simple step will help you maintain your sites in just one server.
Just make sure though that when you try to tweak the file, you make a back up of your install. In this way, you would be able to recover the sites settings should you make a mistake with changing your wp-config.php file.