SLI
In plain terms
A measured indicator of a service's behavior.
Going deeper
A Service Level Indicator is a concrete metric (like request latency or error rate) used to gauge reliability. SLIs feed SLOs.
Under the hood
Good SLIs reflect user experience (e.g., % of requests under 300ms); they're the measurement behind objectives.
Examples
Latency, error rate, availability percentage, throughput, request success.
Think of it like...
Like the actual thermometer reading that tells you if you're meeting your health target.