What are virtualization and KVM?

Virtualization is a very broad term on which everyone could interpret in a different way.

So let me quote the following from the official Ubuntu Server Guide and if you need more details; I could guide you to more resources.

*Virtualization is being adopted in many different environments and situations.

If you are a developer, virtualization can provide you with a contained environment where you can safely do almost any sort of development safe from messing up your main working environment.

If you are a systems administrator, you can use virtualization to more easily separate your services and move them around based on demand.

The default virtualization technology supported in Ubuntu is KVM.

KVM requires virtualization extensions built into Intel and AMD hardware.

Xen is also supported on Ubuntu. Xen can take advantage of virtualization extensions, when available, but can also be used on hardware without virtualization extensions.

Qemu is another popular solution for hardware without virtualization extensions.*

Visualization is running an operating system on top of another operating system. It is a good way to try out new OS's, and several programs exist to let you do this, such as virtual box. KVM is a kernel module (similar to a driver), that allows linux to use build in parts of computer hardware that are designed specially for the purpose of visualization.