SRE Error Budgets & SLIs/SLOs/SLAs.

These are fundamental SRE concepts to balance system reliability with the pace of innovation.

An SLI (Service Level Indicator) is a quantitative measure (e.g., 99.9% of HTTP requests < 200ms). An SLO (Service Level Objective) is the target for that SLI (e.g., maintain 99.9% over 30 days). An SLA (Agreement) is a business contract with financial penalties if SLOs are missed. The Error Budget is the allowable room for failure (100% - SLO = 0.1%). If the error budget is exhausted, feature releases are halted to focus exclusively on reliability.