The practice of Site Reliability Engineering (SRE) applies software engineering skills and principles to improve operational efficiency, data-driven roadmap planning, and general uptime and reliability. SRE is a proactive approach to building and maintaining software that balances innovation with reliability and performance. It involves organizing teams differently depending on the organization and services they support, and it often coexists with DevOps practices. SRE teams are responsible for defining what performant and reliable mean in applications, services, and infrastructure, and they work closely with development and operations teams to understand critical components of their applications and infrastructure. The practice of SRE embraces experimentation, transparency, autonomy, and service levels, which include service level indicators (SLIs), service level objectives (SLOs), and service level agreements (SLAs). Adopting SRE best practices takes time and effort but leads to improved system performance and reliability, benefiting both DevOps teams and customers.