Service Level Indicator (SLI)

A Service Level Indicator, or SLI, is a quantitative metric used to measure the actual performance and quality of an IT service. Common measurements include availability, latency, error rate, throughput and request success rate. An SLI provides specific performance data and frequently serves as the basis for a Service Level Objective, or SLO. While an SLI measures the actual performance achieved by a service, such as its availability, the corresponding SLO defines the desired target value. SLIs are particularly relevant in Site Reliability Engineering, cloud computing, network monitoring and IT Service Management. They enable objective assessment of service quality and help IT teams identify performance issues and systematically monitor the reliability of business-critical IT services.