The chapter delves into the conceptual foundations of ESG criteria, reconstructing their origins and distinguishing them from similar approaches such as Corporate Social Responsibility (CSR), Corporate Sustainability (CS), and Impact Investing (II). ESG is presented not as a mere ethical or reputational constraint, but as a strategic opportunity for the management of non-financial risks with significant economic implications. The chapter highlights the role of ESG in promoting corporate resilience, strengthening stakeholder relationships, and creating long-term value. Central to this is the concept of double materiality, which includes both financial materiality (ESG impacts on economic performance) and impact materiality (the company’s impacts on the environment and society). This perspective is the basis of the most recent European regulatory developments, in particular the Corporate Sustainability Reporting Directive (CSRD) and the European Sustainability Reporting Standards (ESRS). The chapter also analyses the growing integration of ESG metrics in corporate decision-making processes and reporting. Through a critical and structured analysis, the chapter lays the theoretical foundations for understanding how ESG factors are influencing the strategic orientation of contemporary companies.