# High availability

High availability refers to a system or component that is durable and operates continuously without failure for a higher than normal period. Availability is usually expressed as a percentage of uptime in a given year. High Availability relative to “100% operational” or “never failing.”

# Fault tolerant

Fault tolerance is the capability of a component or a computer system to respond to an unexpected software or hardware failure to deliver uninterrupted service and to continue operating properly in the event of the failure of its components.

# Scalability

Scalability is the capability of a system, network, or process to handle an increasing amount of work (load), or its potential to be enlarged to accommodate that growth in load.

# Elasticity

Elasticity is the ability to adapt workload changes by provisioning and de-provisioning resources in an autonomic manner, such that at each point in time the available resources match the current demand as closely as possible.