The practice of SRE is needed for enterprises to develop and operate with a resilience-first approach. In this practice, there is a continuous learning and adaptation cycle of the production systems using SLAs, SLOs, SLIs and Error Budgets. These are tools used to extract the wisdom to know if a system is reliable, available and scalable at the end users required levels. Yes, it is all about the customer. We will take a deep dive in understanding the foundational principles of site reliability engineering and how to implement these tools to fit your unique system needs and business objectives.