FreeBSD has a long and strange history, tracing its roots back to the original Unix from Bell Labs. FreeBSD can almost be seen as the older brother to the younger, more popular Linux. While they are similar, FreeBSD’s long history has given it a very different philosophy and purpose. You can, and many people do, run FreeBSD as a desktop OS, but that’s not where the systems real talent lies. While Linux has tried, and in many cases succeeded, to be everywhere that a kernel can run, FreeBSD has decided that it belongs in the datacenter, a belief that is personified in the FreeBSD slogan, “The Power to Serve”. FreeBSD’s Jails are a great example of where the philosophy of Linux and FreeBSD diverges and produces systems that are functionally similar but logically very different.

In a traditional virtual machine, built the way VMware, Xen, and VirtualBox do VMs, the virtualization application runs an entire operating system as an independent entity.

rest here