This chapter explores the important role of measurement and standardisation in improving sustainability efforts in finance and policy. It starts by emphasising the significance of sustainability metrics and discusses how these metrics are developed, integrated, and applied to evaluate progress in economic, social, environmental, and governance areas. This chapter covers the challenges of creating reliable indicators and addresses issues like greenwashing and inconsistent data. It also explores the landscape of data collection, focusing on methods, ethical concerns, and the need for strong, clear data. A significant emphasis is placed on standardisation, explaining key global and regional frameworks—such as CSRD, ESRS, EU Taxonomy, GRI, ISSB, SFDR, SASB, and others—that promote consistent sustainability reporting. This chapter concludes with a detailed overview of greenhouse gas (GHG) and carbon accounting, presenting the frameworks necessary for trustworthy climate-related disclosures and performance tracking.