Cloud Glossary

Application Domain,   Federation,   Grid/Grid Computing,   Hybrid Cloud,   Image (VM image),   Instance,   On-premise Cloud,   Persistent Storage,   Policy Mediation,   Private Cloud,   Public Cloud,   QoS (Quality of Service),   Quota,   Resources and Resource Pools,   SLA (Service Level Agreement),   Utilization,   Virtualized Data Center

Application Domain
Applications that share a common structure or implement similar functionality are often referred to as belonging to the same "application domain."
Federation
A software architecture in which local administrative control over resources takes precedence over more global control. Typically the owners of a resource agree to "federate" them to a more global infrastructure with the stipulation that they can be withdrawn from the more global context by their owners if needed locally.
Grid/Grid Computing
A "computational grid" is a collection of interconnected, possibly heterogeneous resources that is typically coordinated via process-level middleware. The middleware architectural approach permits grids to incorporate features than enable federation of separate resource pools. Each resource pool in a federation is controlled by its local administrators, providing access to non-local users by pre-arranged agreements between administrators. Grids also expose the heterogeneity of their resources to their users so that each user can choose the collection of resources most appropriate to a specific application.
Hybrid Cloud
A cloud that comprises both public cloud allocations and on-premise cloud allocations
Image (VM image)
A file containing the software components that make up a virtual machine (VM)
Instance
A virtual machine that can be booted under the control of a specific user
On-premise Cloud
A cloud that is implemented in a local data center, typically for the users of that data centers and not the general public.
Persistent Storage
Data storage that is not lost when machine power fails or is turned off.
Policy Mediation
The resolution of potential conflicts between two separately defined policies
Private Cloud
An on-premise cloud that does not interface to the common-carrier Internet
Public Cloud
A cloud that offers utility computing service via an ecommerce-style web interface to users who pay for their usage.
QoS (Quality of Service)
A characterization, either qualitative or quantitative, of the functionality delivered by a service.
Quota
A limit placed by the system on the total resource usage that a particular user can acquire.
Resources and Resource Pools
The term "resources" refers to machines, network components, disk storage, etc. that can be assigned, in whole or in part, to a user or application. A "resource pool" is a collection of unassigned resources that is available to different users and applications.
SLA (Service Level Agreement)
A contract, typically between a service provider and a service client, that stipulates the minimum quality of service the client will receive, the units and measurement methodology that will be used to audit service quality, and the time frame over which it will be measured.
Utilization
A measure of efficiency typically defined to be the percentage of time a resource is busy over a fixed measurement interval
Virtualized Data Center
A data center in which the servers host "virtual machines" that appear to their users to be dedicated physical machines, but which use hypervisors and/or hardware virtualization technology as an actual execution platform.