This thread is meant to be a quick reference to a list of all the more popular virtualization software. The description is copied straight from Wikipedia, so credit is given where due. Obviously checking the product page (product name is hyper-linked to product page for your convenience) or the appropriate Wiki page will yield significantly more information than I have listed here.
First things first...
What is Virtualization?
That's a rather simple answer. Virtualization is simply a software implementation of a machine (i.e. a computer) that executes instructions in the same manner as a physical machine would. This allows one to run numerous "virtual" computers seamlessly on top of their current OS installation. Virtualization is fantastic for businesses to best utilize the hardware they have at hand (i.e. their servers), or for the average user to just fool around with various OSs. Virtualization is a very handy tool for numerous applications.
How do I run a Virtual Machine?
Again, easy. You simply need virtualization software. Below is what I believe to be (and please feel free to chip in if you feel I've left something out) a fairly comprehensive guide of all the popular Virtualization applications.
Virtualbox: "Oracle VM VirtualBox is an x86 virtualization software package, originally created by software company innotek GmbH, purchased by Sun Microsystems, and now developed by Oracle Corporation as part of its family of virtualization products. It is installed on an existing host operating system; within this application, additional guest operating systems, each known as a Guest OS, can be loaded and run, each with its own virtual environment."
VMWare ESX: "VMware ESX is an enterprise-level virtualization product offered by VMware, Inc. ESX is a component of VMware's larger offering, VMware Infrastructure, which adds management and reliability services to the core server product. ESX is being replaced by ESXi (see below)."
VMWare ESXi: "VMware ESXi is a smaller footprint version of ESX that does not include ESX's Service Console. It is available as a free download from VMware though certain features are disabled without the purchase of a vCenter license."
VMWare Vsphere: "VMware vSphere, (formerly VMware Infrastructure 4) is VMware's first cloud operating system. It is able to manage large pools of virtualized computing infrastructure, including software and hardware."
VMWare Workstation: "VMware Workstation is a virtual machine software suite for x86 and x86-64 computers from VMware, a division of EMC Corporation. This software suite allows users to set up multiple x86 and x86-64 virtual computers and to use one or more of these virtual machines simultaneously with the hosting operating system. Each virtual machine instance can execute its own guest operating system, such as Windows, Linux, BSD variants, or others. In simple terms, VMware Workstation allows one physical machine to run multiple operating systems simultaneously. Other VMware products help manage or migrate VMware virtual machines across multiple host machines."
VMWare Fusion: "VMware Fusion is a virtual machine software product developed by VMware for Macintosh computers with Intel processors. Fusion allows Intel-based Macs to run x86 and x86-64 "guest" operating systems, such as Microsoft Windows, Linux, NetWare and Solaris as virtual machines simultaneously with Mac OS X as the "host" operating system using a combination of paravirtualization, emulation and dynamic recompilation."
VMWare Player: "VMware Player is a freeware virtualization software product from VMware, Inc. (a division of EMC Corporation). VMware Player can run virtual appliances. VMware Player can also create virtual machines since version 3.0. It uses the same virtualization core as the VMware Workstation product."
VMWare Server: "In computing, VMware Server (formerly VMware GSX Server) is an entry-level virtualization-software server suite developed and promoted by VMware, Inc., a subsidiary of EMC Corporation. VMware Server can create, edit, and play virtual machines. It uses a client–server model, allowing remote access to virtual machines, at the cost of some graphical performance (and 3D support). In addition to the ability to run virtual machines created by other VMware products, it can also run virtual machines created by Microsoft Virtual PC. VMware, Inc. makes VMware Server freely available in the hope that users will eventually upgrade to VMware ESX."
KVM: "Kernel-based Virtual Machine (KVM) is a Linux kernel virtualization infrastructure. KVM supports native virtualization on x86 processors that provide Intel VT-x or AMD-V extensions; it has also been ported to S/390, PowerPC, and IA-64, and an ARM port is in progress."
Xen: "Xen is a virtual-machine monitor for IA-32, x86-64, Itanium and ARM architectures. It allows several guest operating systems to execute on the same computer hardware concurrently. The University of Cambridge Computer Laboratory developed the first versions of Xen; as of 2010 the Xen community develops and maintains Xen as free software, licensed under the GNU General Public License (GPLv2)."
Windows Virtual PC: "Windows Virtual PC (formerly Microsoft Virtual PC and Connectix Virtual PC) is a virtualization program for Microsoft Windows. Virtual PC virtualizes a standard PC and its associated hardware. Supported Windows operating systems can run inside Virtual PC. Other operating systems like Linux may run, but are not officially supported."
Which applications will work with my OS?
Windows - Virtualbox, VMWare Workstation, VMWare Player, VMWare Server, Windows Virtual PC Linux - Virtualbox, VMWare Player, VMWare Server, KVM, Xen OS X - VMWare Fusion Standalone - ESX, ESXi, VMWare vSphere
Alright, well that covers most of the basics. Again, I'd like for the community to contribute to this thread, so let me know what you all think. The good, the bad, etc. If I missed any vital information, software, or whatever, please let me know.