This Global Impact Investing Network (GIIN) primer is included as a core reference for Part 2’s Impact Investment chapter because it authoritatively defines impact investing—investments made with the intention to generate positive, measurable social or environmental impact alongside a financial return—outlines the four core elements (intentionality; use of evidence and impact data; management of impact performance; and contribution to industry growth), describes who makes impact investments and how they typically perform, provides global case studies and practical measurement resources, and reports the market size (estimated at $1.571 trillion, with rapid growth reported since 2019); together these elements support the book’s framing of values‑led portfolio construction, demonstrate that impact and financial returns can align, and offer readers concrete guidance and sources for building and measuring purposeful investments.