High availability (HA) is a characteristic of a system designed to ensure a high level of operational performance and minimal downtime. HA systems are structured to remain functional and accessible even in the event of hardware failures, network issues, or other disruptions. This is achieved through redundancy, failover mechanisms, load balancing, and regular maintenance. High availability is crucial for critical applications and services that require constant uptime, as it helps maintain business continuity and reliability by reducing the risk of outages and service interruptions.