Definition: Availability is that component of information assurance that focuses upon providing immediate access to mission critical data when it is needed for decision making. Otherwise, being unable to access needed information would be very negative to an organization's productivity.
Its Relevance: An organization's business continuity is at serious risk if the information that is required for decision making is inaccessible. Failing to provide timely access to vital information resources can result in the continuity of operations being lost. A company may, otherwise, be considered as negligent and legally liable for failing to meet a due diligence standard.
Access to information must be systematically assured or an organization is vulnerable and subject to the multiple threats such as a Denial of Service (DOS) attack or a Distributed Denial of Service Attack (DDOS).