This document provides an introduction to cloud engineering and site reliability engineering (SRE). It begins with a brief history of cloud computing and its emergence in the 2000s with services from Amazon, Google, Microsoft and others. It describes the roles of operators in ensuring stability and developers in pursuing agility. It defines key concepts like DevOps, SRE, and cloud computing. It discusses how DevOps breaks down silos between operators and developers. It also provides examples to illustrate why cloud infrastructure is important and offers resources for learning more.