It's usually called a hypervisor, or virtual machine monitor.
Virtual Layer
A 'virtual machine' is a software program which emulates another machine type. The virtual machine behaves exactly like the machine it emulates but uses the physical hardware of the machine it is running on. In other words, it translates calls intended for the virtual machine into calls that will execute upon the physical machine, effectively acting as an interpreter between the two machines.
A 'virtual machine' is a software program which emulates another machine type. The virtual machine behaves exactly like the machine it emulates but uses the physical hardware of the machine it is running on. In other words, it translates calls intended for the virtual machine into calls that will execute upon the physical machine, effectively acting as an interpreter between the two machines.
JVM stands for Java Virtual Machine, it is software.
Virtual Machine software does not lag if you allocate appropriate resources to it. If it is lagging, I suggest adding a processor core or increasing the RAM on your virtual machine.
A Java Virtual Machine enables a set of computer software programs and data structures to use a virtual machine model for the execution of other computer programs and scripts. The model used by a JVM accepts a form of computer intermediate language commonly referred to as Java bytecode. A virtual machine is a software implementation of a machine (i.e. a computer) that executes instructions (not programs) like a physical machine.
You can find information on how to use virtual machine software under Ubuntu on several websites such as Ubuntu Documentation, Ubuntu Forums and Download Squad.
In computer science, a virtual machine is software that creates a virtualized environment between the computer platform and its operating system, so that the end user can operate software on an abstract machine. For the source and more detailed information concerning this subject, click on the related links section (Answers.com) indicated below this answer box.
To download a virtual machine, one should try download sites such as Oracle for this software. Alternatively, try webpages such as VM Ware, for example.
Here's a Wikipedia article for an overview: http://en.wikipedia.org/wiki/Virtual_machine and a specific product: http://www.vmware.com/ Here's a company that sells virtual machine software: http://www.virtualbox.org/ . A general overview: http://www.wisegeek.com/what-is-a-virtual-machine.htm
Virtual Machine
This is usually called emulation.