The term “virtual machine” is an umbrella term referring to a range of downloads that can emulate software and operating systems and run various operating systems and virtual servers. Each of the virtual machine downloads has a separate and distinct purpose, and some are used every day without the user knowing he or she is using a virtual machine.
Virtual machine downloads that emulate software are commonly made for those who run operating systems that do not see many software releases. The virtual machine is able to emulate another operating system’s environment, one for which adequate software is released, and allows the user to run the program. These are generally process virtual machines, or machines made to perform a single function, and typically do not force the user to purchase or use an installation CD for the operating system the software is emulating.
System virtual machine downloads are made to emulate entire operating systems. This is done by making a partition on the computer’s hard drive and storing data for the extra operating system on that partition. Some of these programs run the separate operating system in a different window, while others have to start up the other operating system separately. Depending on the program, these virtual machine downloads may be able to emulate one or several different operating systems. An installation CD generally will be needed for this virtual machine to emulate the operating system.
A virtual PC is similar to a system virtual machine in that it emulates operating systems. The difference here is that a virtual PC does not emulate different operating systems but allows the user to open the same operating system several times at once on the same window. This is used primarily by programmers to provide testing environments for new codes or programs without the chance of ruining the computer.
Virtual servers are unlike the other categories of virtual machines. When someone purchases a domain and hosts a website, a server is necessary to place the website on the Internet. Web hosting companies use a virtual server that allows them to make a partition on the server and place the website information in that partition. This allows the website owner to run and operate a website without having to purchase an entire server. The website owner does not have a physical server he or she can control, but he or she also doesn't have the high costs associated with running a physical server.