High Availability
In plain terms
Designing systems to stay operational with minimal downtime.
Going deeper
High availability uses redundancy, failover, and health monitoring to keep services running through failures, often targeting uptime like 99.99%. It removes single points of failure.
Under the hood
Measured in 'nines' (99.9% ≈ 8.7h/yr downtime); achieved via redundancy across failure domains, eliminating single points of failure.
Examples
Multi-AZ/region, active-active clusters, redundant load balancers, health checks.
Think of it like...
Like a hospital with backup power, spare staff, and duplicate equipment so it never stops operating, even during a crisis.