This document discusses systems thinking and key concepts related to systems. It defines systems thinking as the cognitive process of studying and understanding systems of any kind by examining the linkages and interactions between interconnected components. A system is defined as a set of elements organized in a structure that produces characteristic behaviors. Key components of systems include elements, interconnections, and function. The document contrasts System 1 and System 2 thinking and provides examples. It emphasizes that systems thinking is needed to address problems created by more simplistic levels of thinking.