In the old days, a new server was bought for every application you could think of. Data centers were full of hardware, sometimes critical hardware was on the floor with the cables coming out of the racks, threatening bot business and the manager but still running that superimportant application that made all the money....
Today's *hot* word is virtual. About ten years back companies started to use servers for several applications, and now we're putting virtual servers on servers that run multiple applications. Why are we doing this ? For the money ? Not directly. There are a few advantages in virtualization, if you do it the right way :

• Bigger, but less hardware keeps your data center nice and tidy.
• More virtual servers guarantee application uptime, bringing money in
• Virtual hardware is easier to maintain from a remote location
• Installing a new server can be done by running a script
• More virtual servers will allow you to put more apps on the same hardware as the applications don't interfere with one another

I think I can go on for a while, but this should cover the most important issues. This technology has no meaning for those people who run a server at home - but for business it can be of major importance....