This chapter introduces key concepts about financial markets and institutions. It discusses why studying financial markets and institutions is important, as they are primary channels for allocating capital in society. The chapter defines different types of financial markets, including primary versus secondary markets, and money versus capital markets. It also introduces various financial instruments and derivative markets. Additionally, it provides an overview of different types of financial institutions and how they benefit both suppliers and users of funds. The chapter concludes with discussions around regulation of financial markets and institutions.