Metal as a Service – MAAS – lets you treat physical servers like virtual machines in the cloud. Rather than having to manage each server individually, MAAS turns your bare metal into an elastic cloud-like resource.
MAAS "Metal as a Service" is similar to IAAS "Infrastructure as a Service" as it allows a new machine to be provisioned. The difference is that IAAS normally refers to virtual machines, MAAS is designed to provision bare metal. This means bring a bare metal server with no operating system install to a completely working server ready for the user to deploy services on.