quantitative measure of some aspect of a service Service Level Objective (SLO) target value or range for a service, measured by an SLI Service Level Agreement (SLA) contract with your users that includes consequences of meeting or missing the SLOs landing.google.com/sre/book/chapters/service-level-objectives.html request latency, error rate, availability 99th percentile for request latency of 100ms or less public service: 10% discount for every hour below SLO, internal service: team gets paged