SLA vs. SLO - What's the Difference Between a Service Level Agreement and a Service Level Objective?

This article explains the difference between Service Level Agreements (SLAs) and Service Level Objectives (SLOs). SLAs are legally binding contracts with customers defining service expectations (like uptime), while SLOs are internal targets set by engineering teams to ensure they meet those contractual obligations. SLOs act as a buffer – allowing for a controlled amount of “failure” (error budget) – to proactively address issues before they impact customers and trigger penalties outlined in the SLA.