Contracts signed between a vendor and customer that guarantees a certain measurable level of service.

They are often drawn up with specific financial consequences if the vendor fails to provide the guaranteed service. SLAs are usually composed of many individual Service Level Objective (SLO) to help formalize the details of what is being promised. For example, an SLA between a web host provider and a customer can guarantee 99.95% uptime for all web services of a company over a year.