Virtualization is the process of creating a lot of machines on one machine , as if they work separately.This technology is becoming very popular due to its benefits . To understand it well , let's consider 3 protocols of virtualization : Application / OS / hardware , when virtualization is used we can considder that there are more than one application and each one is working on its OS: Application(i)/OS(i)/virtualization layer/OS for (i..to n). (n number of VMS)The hypervisor is necessary to the virtualization , it attributes to each VM its needs as ressources in terms of CPU/RAM/Go/IOPS , and makes sure that there are no interactions between the VMS , there are two types of hypervisors "bare metal" and "hosted" : the type bare metal use those layers: OS/HYPERVISOR/HARDWARE but the type hosted uses OS/HYPERVISOR/OS/HARDWARE.types of virtualization : there are also many other types of virtualization in total (virtualization of servers,of session , of applications , of desktop , of networks , and of storage..), in this articlejust some types will be explained.virtualization dekstop by using VDI :VDI : Virtual Desktop Infrastructure is used in this case and also a VDA Agent , this kind of virtualization uses those technologies to work on a data center which is far from the place on which he works but by using this technolgy , the picture is transmitted of the desktop . this enables a worker to work on datas which are far from him and to manipulate then as he wants. any work is associated to a user profile. he works on his desktop .virtualization of session :a lot of users are connected on one single server , as the case of a terminal server , and any user works on this server as if he's alone.Virtualization of an application :An application is streamed , and navigates on its own bubble , it can be used without an installation. With high performance.Designing a project of virtualization : Before starting any virtualization project , we must make a conception of it , we must answer a question : how much ressources of CPU/RAM/IOPS/GO is used according to a period ? and this period must be long and well chosen. . the society must then definite its ROI and its TCO. and also thinks about the consequences of the designed architecture for example : if 16 CPU , and 32 Go Ram is used , we can have multiple approachs of virtualization : 4 Srv : 4 CPU / 8Go Ram orusing 2 Srv : 8 CPU/ 16Go Ram ; in the first case if one server falls , 1/4 of machines will be impacted,but in the second case 1/2 of servers will be impacted.Benefits of virtualization : the virtualization changed our way of using technology from the BYOC approach to the BYOD approach : "bring your own computer" to "bring your own device" , in fact it has a lot of benefits which can be noticed from real cases. In fact in first virtualization was used , because it was noticed that no one uses completely the total resources of their servers in any infrastrcuture : 70% of resources are not used , so thanks to the virtualization , which is a flexible solution , we can use the number of VMS we need on a datacenter , and add our vms according to our needs , in addition to that , when virtualization is used we can reduce our consommation of power , electricity , climatization, virtualization is very useful to guarantee a flexbile , secured , ease of use to the infrastructure . And also , with virtualization it's possible to use multiple version of a software : for example : let's consider a society which uses files of Excel 2003 and wanted to immgirate to Excel 2010 , by without loosing the ability of opening the files which were created by Excel old version, virtualization guarantee this compatibility.