Transparency is a term that has attained quasi-religious significance in debate over governance and institutional design. Today, it is pervasive in the jargon of business governance as well as that of governments and international bodies, and has been used almost to saturation point in all of those domains over the past decade. This chapter maps out some of the different strains and meanings of the term and doctrine. Like many other notions of a quasi-religious nature, transparency is more often preached than practised, more often invoked than defined, and indeed might ironically be said to be mystic in essence, at least to some extent. The English philosopher Jeremy Bentham seems to have been the first to use ‘transparency’ in its modern governance-related sense in English. The chapter also discusses transparency in international governance, transparency in national and sub-national government, and transparency and corporate governance.