What Is a Service Level Objective (SLO)?
A service level objective (SLO) is an internal reliability target for a measurable aspect of a service, such as "99.9% of requests succeed" or "p99 latency under 300ms." It is the goal a team commits to and measures itself against. SLOs make reliability concrete and give error budgets their boundary.
Why it matters
Without an explicit target, "reliable enough" is a matter of opinion. An SLO sets a clear, measurable bar that aligns engineering effort, defines when to invest in stability, and underpins the error budget that governs release pace.
Related concepts
- An SLI is the metric an SLO sets a target on
- An SLA is the external, contractual cousin of an SLO
- Error budgets derive from the SLO
Related guides
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