Chapter 4. Now Casting and the Real Time Data Flow The term now casting is a contraction for now and forecasting and has been used for a long time in meteorology and recently also in economics. In this chapter we survey recent developments in economic now casting with special focus on those models that formalize key features of how market participants and policymakers read macroeconomic data releases in real time which involves monitoring many data forming expectations about them and revising the assessment on the state of the economy whenever realizations diverge sizeably from those expectations.