The Impact Investing Institute’s “Introduction to impact investing” is included as a foundational, authoritative overview for PART 2: The Purposeful Investment Landscape; it clearly defines impact investing and situates it alongside traditional, responsible and sustainable investing, introduces the spectrum of capital, and summarises the history, key global frameworks (UN SDGs, Impact Management Project, IFC) plus the main challenges and opportunities—making it an ideal primer that supplies the definitions, frameworks and further reading the chapter on Impact Investment needs before progressing to more advanced material.