From Wiki:
Platform as a service (PaaS) is the delivery of a computing platform and solution stack as a service. It facilitates deployment of applications without the cost and complexity of buying and managing the underlying hardware and software layers, providing all of the facilities required to support the complete life cycle of building and delivering web applications and services entirely available from the Internet—with no software downloads or installation for developers, IT managers or end-users. It's also known as cloudware.
VirtualLabs is a complete PaaS solution that enables building a full testing environment in the cloud.
