Conclusion

At this point, we've seen a UML from both the inside and the outside. We've seen how a UML can use host resources for its hardware and how it's confined to whatever has been provided to it.

A UML is both very similar to and very different from a physical machine. It is similar as long as you don't look at its hardware. When you do, it becomes clear that you are looking at a virtual machine with virtual hardware. However, as long as you stay away from the hardware, it is very hard to tell that you are inside a virtual machine.

Both the similarities and the differences have advantages. Obviously, having a UML run applications in exactly the same way as on the host is critical for it to be useful. In this chapter we glimpsed some of the advantages of virtual hardware. Soon we will see that virtualized hardware can be plugged, unplugged, extended, and managed in ways that physical hardware can't. The next chapter begins to show you what this means.