Tail Latency

Tail latency describes the slow end of a response-time distribution, often expressed through high percentiles such as the 95th or 99th percentile. A service can have a low average while a meaningful fraction of users experience long waits.

Requests that depend on many downstream operations are particularly sensitive to individual slow components. Percentile interpretation requires a defined measurement window and workload rather than treating one unusually slow sample as a complete distribution.