# Content The Corruption Perceptions Index scores and ranks countries/territories based on how corrupt a country’s public sector is perceived to be. It is a composite index, a combination of surveys and assessments of corruption, collected by a variety of reputable institutions. The CPI is the most widely used indicator of corruption worldwide. Corruption generally comprises illegal activities, which are deliberately hidden and only come to light through scandals, investigations or prosecutions. There is no meaningful way to assess absolute levels of corruption in countries or territories on the basis of hard empirical data. Possible attempts to do so, such as by comparing bribes reported, the number of prosecutions brought or studying court cases directly linked to corruption, cannot be taken as definitive indicators of corruption levels. Instead, they show how effective prosecutors, the courts or the media are in investigating and exposing corruption. Capturing perceptions of corruption of those in a position to offer assessments of public sector corruption is the most reliable method of comparing relative corruption levels across countries. # Acknowledgements The data sources used to calculate the Corruption Perceptions Index scores and ranks were provided by the African Development Bank, Bertelsmann Stiftung Foundation, The Economist, Freedom House, IHS Markit, IMD Business School, Political and Economic Risk Consultancy, Political Risk Services, World Bank, World Economic Forum, World Justice Project, and Varieties of Democracy Project.