Summary

You can now reason about a service's reliability targets the way the reliability standard does, not just recite the word "SLO."

In this module, you:

• Learned the thesis that reliability is a budgeted feature, not an absolute, and why that makes SRE an engineering discipline rather than a renamed ops rota.
• Set an SLO from a critical user journey, picked the right tier target, and computed the error budget and burn rate it produces - 99.9% over 30 days buys about 43 minutes.
• Read the error-budget policy - healthy vs. exhausted vs. repeated breach - and named its one accountable owner, the reliability champion.
• Saw what operating on that budget buys: sustainable on-call, a capped and automated toil load, tested resilience through capacity and chaos, and an SLA that is always looser than the SLO behind it.

Next steps

• reliability.md - keep it open whenever you set or review a real service's SLO.
• ADR-0020 - the governance decision behind the error-budget policy.
• Continue the Operate the estate path with Respond to incidents, where a burn-rate page becomes a declared incident under the severity matrix.