# What is Service Level Objective (SLO)?

> An internal reliability target, like 99.9% of requests succeeding.

Canonical: https://www.decimal.app/glossary/slo · Last reviewed: 2026-09-23

An SLO sets a target for a measurable service indicator, such as availability or latency, over a time window. The gap between the target and 100% is the error budget.

## Why it matters

SLOs give engineering a shared definition of 'reliable enough'. Support ticket trends are a useful check on whether the SLOs reflect what customers feel.

## Best practices

1. Measure what customers experience. Not just server health.
2. Spend the error budget deliberately. Use it to ship faster when you have room.
3. Compare with ticket data. If tickets spike while SLOs look fine, the SLO is measuring the wrong thing.

## How Decimal helps

Decimal's investigations show which customer-reported problems trace back to reliability issues, adding a customer-side signal to your SLOs.

## Related terms

- [Service Level Agreement (SLA)](https://www.decimal.app/glossary/sla): A contractual commitment on response or resolution times.
- [Observability](https://www.decimal.app/glossary/observability): How well you can understand a system's internal state from the data it emits.
- [Incident](https://www.decimal.app/glossary/incident): An unplanned disruption or degradation of a service that needs an urgent response.

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