Fault Tolerance
In plain terms
A system's ability to keep working despite failures.
Going deeper
Fault tolerance lets a system continue operating correctly even when components fail, through redundancy and graceful degradation. Failures don't take it down.
Under the hood
Achieved via replication, failover, and isolation; aims to avoid single points of failure.
Examples
Redundancy, failover, replication, high availability, resilient systems.
Think of it like...
Like a plane that keeps flying safely even if one engine fails.