SLA

Service Level Agreement

Contractual promise about uptime/performance, often with penalties.

When you'd see it: Vendor contracts and operations. "99.9% uptime SLA" is a contractual promise.

Why it matters: An SLA is a formal commitment to a level of service, usually with penalties if it is missed. It turns "we'll be reliable" into a measurable, enforceable number.

Common mistakes: Confusing the SLA (the external promise, with consequences) with the SLO (the internal target). The SLA is what you owe the customer. The SLO is the stricter goal you hold yourself to.