Glossary

SLA and SLO (service level agreement vs objective)

An SLA (Service Level Agreement) is a contract between a service provider and a customer that specifies measurable guarantees — typically availability, latency, or error rate — with financial or legal consequences for breaches. An SLO (Service Level Objective) is the internal engineering target, deliberately set stricter than the SLA to create an error budget: a cushion that allows teams to detect and fix problems before the external contract is violated.

Formula: Example: SLA 99.9% availability vs internal SLO 99.95% — the gap is error budget before the customer-facing SLA is breached.

Last updated: March 2026