A virtual machine is a type of computer application used to create a virtual environment, which is referred to as virtualization. Virtualization allows the user to see the infrastructure of a network through a process of aggregation. Virtualization may also be used to run multiple operating systems at the same time. Through the help of a virtual machine, the user can operate software located on the computer platform.

There are several different types of virtual machines. Most commonly, the term is used to refer to hardware virtual machine software, also known as a hypervisor or virtual machine monitor. This type of virtual machine software makes it possible to perform multiple identical executions on one computer. In turn, each of these executions runs an operating system. This allows multiple applications to be run on different operating systems, even those they were not originally intended for.

Through the use of the hardware virtual machine software, the user has a seemingly private machine with fully functional hardware that is separate from other users. Hardware virtual machine software also makes it possible for users to boot and restart their machines quickly, since tasks such as hardware initialization are not necessary.

Virtual machine can also refer to application virtual machine software. With this software, the application is isolated from the computer being used. This software is intended to be used on a number of computer platforms. This makes it unnecessary to create separate versions of the same software for different operating systems and computers. Java Virtual Machine is a very well known example of an application virtual machine.

A virtual machine can also be a virtual environment, which is also known as a virtual private server. A virtual environment is used for running programs at the user level. Therefore, it is used solely for applications and not for drivers or operating system kernels.

A virtual machine may also be a group of computers that work together to create a more powerful machine. In this type of virtual machine, the software makes it possible for one environment to be formed throughout several computers. This makes it appear to the end user as if he or she is using a single computer, when there are actually numerous computers at work.