What is SLO (Service Level Objective)?
A Service Level Objective is a target reliability threshold for a service, like 99.9% of requests succeeding over 30 days, that teams measure against and use to decide whether they can ship risk or must slow down.
A Service Level Objective (SLO) is an explicit, measurable target for how reliable a service should be over a rolling window. It is built on top of one or more Service Level Indicators (the raw measurements, such as the fraction of successful requests or the share of requests served under 200ms) and expresses the line the team commits to staying above, for example 99.9% availability over 28 days. SLOs matter because reliability is not free: chasing perfect uptime starves feature work, while ignoring reliability burns user trust. An SLO turns that tradeoff into a number everyone agrees on, and the gap between the SLO and 100% becomes the error budget the team is allowed to spend on risk, deploys, and experiments. SLOs are the backbone of modern reliability practice, distinct from external SLAs (contractual promises with penalties) and from internal SLIs (the metrics themselves). For AI agents working an incident or a capacity question, knowing the SLO is essential context: an agent that records and recalls a service's SLO, its current burn rate, and past breaches through a shared memory layer can reason about whether a proposed change is safe instead of asking a human every time.