Service level agreements have always existed in the tech market but have become much more prevalent thanks to cloud, and especially public cloud provision.
Service levels agreements are the documents you must read before you sign the cloud contract.
Public cloud SLAs tend to focus on promising certain levels of performance and guaranteed access.
They tend not to focus on resilience, security or flexibility.
The Cloud Council, in April last year produced cloud service agreements a practical guide, in which it changed Service to a subset of Cloud Service Agreement.
It says
A typical Service Level Agreement (SLA) within the CSA describes levels of service using various attributes such as availability, serviceability or performance. The SLA specifies thresholds and financial penalties associated with violations of these thresholds. Well-designed SLAs can significantly contribute to avoiding conflict and can facilitate the resolution of an issue before it escalates into a dispute. To guarantee an agreed service level, service providers must measure and monitor relevant metrics. There is often a mismatch between the metrics collected and monitored by the service provider and the higher-level functional (or “end-to-end”) metric relevant to customers. This issue is common across service models, but is more acute for SaaS since customers want service levels to be met at the application level where they can be impacted by many factors. This is one reason why CSAs for SaaS usually lack stringent service level guarantees. Service level guarantees for IaaS are better defined than for SaaS or PaaS, but that does not mean that they meet the customer’s expectations. Most public cloud infrastructure services are available only through non-negotiable standard contracts which strictly limit the provider’s liability. As a result, the remedies offered in case of non-compliance do not match the cost to the customer of the potential service disruptions. Furthermore, most IaaS providers put the burden of SLA violation notification and credit request on their customers.
http://www.cloud-council.org/deliverables/CSCC-Practical-Guide-to-Cloud-Service-Agreements.pdf