Virtual machines and virtualization

In order to understand VMs and virtualization, let's first look at an analogy. For many of us, one of our goals is to own a house. Can you picture it? Three bedrooms, a beautiful lawn, and a white picket fence, maybe? For some of us, at least for now, that dream may not be achievable, so we must settle to rent an apartment in a big building.

You can think of the beautiful house as a normal standalone server dedicated to serving only one client or one application. The apartment in this case is the VM. The apartment serves its purpose by providing housing with some shared services. It might not be as beautiful and convenient as the house, but it does the job. With the house, if you live alone, you are wasting resources because you can only use one room at a time. Similarly, with a standalone server, especially if you have an application with variable traffic, you will have lulls in your traffic where a lot of the capacity of the machine is...