Description: Decentralized finance, or DeFi, is an emerging financial system powered by blockchain technology. This research report aims to introduce actuaries to DeFi and help them develop a solid understanding of DeFi. It will begin with addressing “what is DeFi?” by providing an introduction on blockchains and DeFi. It will then discuss in further detail the key characteristics, applications, opportunities, and risks of DeFi. After providing the foundation, this report will discuss the potential adoption of DeFi and its interaction with the current financial system (sometime referred to as traditional finance for contrast with DeFi), and the implications for practicing and aspiring actuaries. In addition, a glossary of terms used in DeFi and a brief history of the development of DeFi have been included in the appendix.