This introductory chapter outlines the distinctions between, on the one hand, political and bureaucratic corruption, and, on the other hand, between extractive and power-preserving corruption. It is argued that the two distinctions are important to understand the breadth and depth of political corruption: political corruption is two interrelated processes that often destroy economies and democracies. The first is what is called extractive political corruption, which is when political power-holders are enriching themselves by abusing their hold on power to extract from public and private resources. Extractive political corruption is bribery, embezzlement, and fraud for the benefit of individual power-holders and for the regime as such. Bribe taking in public procurement processes is often the biggest source. The second is what is called extractive political corruption, which is when political power-holders are using the corruptly acquired means (and other state resources and privately held means), in illicit or immoral ways, to maintain and/or strengthen their hold on power. Power-preserving political corruption is to build political support, protection and impunity. It includes favouritism (of which nepotism and clientelism is well known), co-optations and the fraudulent manipulation of institutions. The buying of votes in elections and parliaments is often a part of the picture. Finally, the chapter argues that the distinction has wide-ranging consequences for research on corruption, because these qualitatively distinct social phenomena require different analytical frameworks, conceptual models, and investigation and data collection methods.