• A virtual machine (VM) server is a system that will host multiple virtual machines running their own instance of an operating system. This can be done in one of two modes; fully virtual, and paravirtual.

• A Virtual Machine is a self-contained operating environment that behaves as if it is a separate system. Basically it is a software implementation of a system that executes programs like a physical machine. What makes Virtual Machines's so nice is that you can have one physical computer with a Virtual Machine Server and host multiple Virtual Machines that each have their own purpose. Web server and DNS are a couple examples

• Xen is the virtual machine manager (VMM) that we use in lab46 to have a virtual machine server. It is what allows us to run multiple computer operating systems to execute on the same computer hardware concurrently.

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• A virtual machine running in Fully Virtual mode will completely emulate all hardware devices. In Xen this is known as a hardware virtual machine or hvm. An example of a fully virtual machine is an snes emulator, as the special hardware needed for the snes must be virtualized.

• A virtual machine that is running in Paravirtual mode does not need to completely emulate hardware devices. This is the mode our virtual machines in lab46 use. Xen will call a virtual machine running in this mode pvm.

• An emulator is hardware or software or both that duplicate the functions of hardware(guest) in another system with different hardware(host), so that the emulated behavior closely resembles the behavior of the guest. My laptop runs completely different hardware than a nintendo but through software I can emulate the nintendo and play games on my laptop.

• Popek and Goldberg virtualization requirements are a commonly used set of conditions to determine if a system can efficiently support virtualization.

• An Embedded System is a computer system designed for specific function as is a part of a larger system. Cell phones(non smart) and microwaves are examples of embedded systems, they have a specific function and can't do much beyond that function.

• a Distributed System consists of multiple computers connected through a network that work together in order to achieve a common task. Each primary task is broken up into smaller tasks and each subtask is completed by one ore multiple computers until everything is complete.