Earlier, applications have run directly on an OS on a PC or a server. Each PC or server would run only one OS at a time. Therfore, the coders had to rewrite parts of applications for each OS/platform they wanted to run on. To tackle the problem they came up with the concept called Virtualization . Virtualization technology enables a single PC or server to simultaneously run multiple operating systems , devices with virtualization can host numerous applications, including those that run on different operating systems therefore making the application more accessable . In essence, the host operating system can support a number of virtual machines (VM) , each of which has the characteristics of a particular OS .
The VM approach is becoming a common way for businesses and individuals to optimize their hardware usage by maximizing the number of kinds of applications that a single computer can handle , that is optimizing the memory on that device.Commercial VM offerings by companies such as VMware and Microsoft are widely used. VM technologies also are used in desktop environments to run multiple operating systems, such as Windows , Linux , etc.
The virtual machine monitor (VMM) , or hypervisor , runs on top of (or is incorporated into) the host OS. The VMM supports VMs, which are emulated hardware devices. Each VM runs a separate OS. The VMM handles each operating system’s communications with the processor, the storage medium, and the network. To execute programs, the VMM hands off the processor control to a virtual OS on a VM. Most VMs use virtualized networkconnections to communicate with one another, when such communication is needed.
For eg: One can run different site's in different OS on the same device using Virtualization, the benefit of virtualization is that even if one of the site crashes for some reason others are not affected and smooth functioning takes place otherwise if they are working in same server or OS every site will be affected , VM is a cheaper option than to buy a server which not only is costly but also doesn't use memory efficiently
