In the previous lesson, we made the assertion that the reliability of a system is its most important feature. Taking this to extremes is counterproductive for any business. It's totally possible to build a super reliable system that has no features and never changes, but it's hard to make any money by doing that. For most businesses, there is a constant pressure for new features to drive user acquisition and revenue growth, and balancing this demand with the need to maintain system reliability is quite challenging. Targeting a specific level of reliability is key to establishing that balance. We call these targets Service Level Objectives or SLOs. The main question SLOs can help executives and product teams answer is if reliability is a feature, how do you prioritize it versus other features? Setting a target for system reliability and communicating that target widely allows all parts of your organization to determine independently whether or not the service is reliable enough. Acknowledging that a specific quantity of unreliability is acceptable provides a budget for failure that can be spent on developing and launching new features. The remaining budget provides a signal defeat in your planning cycles to ensure work to improve reliability is prioritized. The incentives for all parts of your organization are aligned towards the goal of making your system reliable enough. SLOs provide a common language and shared understanding between different parts of your organization, anchoring the reliability conversation on concrete data. It's tempting to consider SLOs to be solely an operational concern, but for them to function correctly as a prioritization signal, the target must be set in conjunction with engineering and product teams. Everyone must agree that the target accurately represents the desired experience of your users.