| 1. Availability is the amount of time that a system will be available. It is calculated as a percentage of an elapse year.|
leg of the information security principles, which is Confidentiality, Integrity and Availability.
| 2. An umbrella term that includes reliability (including resilience), maintainability, serviceability and security. A common definition of availability is 'the ability of a component or Business Continuity (under combined aspects of its reliability, maintainability and security) to perform its required function at a stated instant or over a stated period of time'. Service availability is sometimes expressed as an availability percentage, i.e. the proportion of time that the service is actually available for use by the customers within the agreed service time.
(Source: ENISA - the European Network and Information Security Agency. BCM & Resilience Glossary)