SLO
A practical DevOps definition, with an example you can use.
A service-level objective: a target for a measured aspect of service reliability over a defined window.
An example you can picture
A team defines a target for the proportion of successful requests during a rolling period, then uses that target to discuss reliability work and release risk.
The distinction that matters
An SLO is a target; an SLI is the measurement. An SLA is an agreement and may include contractual consequences.
Put it into practice
Define one indicator and a realistic target for a practice service. State the measurement window and exclusions explicitly. Explain how the target would inform a decision about reliability work.
Connect the ideas: availability and metrics. For the bigger picture, read the related learning guide.
Reference
Read the primary documentation for the underlying concept and further detail.