High Availability: The design and implementation of systems and processes to ensure that a service remains available at a high level over a defined period. This often involves redundancy, failover, load balancing, and other mechanisms to minimize downtime in the event of an outage or failure. From a security perspective, high availability is important not only for maintaining business operations but also for sustaining security controls and processes. An HA design can help prevent service disruptions that could be exploited by attackers, or that could lead to other security vulnerabilities.