Majority of software engineering thought happens in development, not in maintenance If software engineering focuses on designing and building, another discipline is needed to focus on the lifecycle of software products Applying principles of computer science and engineering to design and development of computing systems, typically large distributed ones Focus on reliability: a system isn’t useful if it isn’t working finding ways to make systems more scalable, reliable, and efficient up to a certain point, when new features can be added Operating services built on top of computing systems to keep them running Like security, the earlier you worry about reliability, the better Less costly to expand and existing structure than introduce one that isn’t present First SRE? Margaret Hamilton, worked on Apollo program on loan from MIT >  part of the culture was to learn from everyone and everything, including from that which one would least expect.