This Research Review presents a compilation of key papers chronicling the evolution of the economics of information into the economics of knowledge. It traces the unfolding of the fertile ambiguity and ambivalence of the notion of information with the identification and eventual separation of its two basic, quite distinct meanings: knowledge and signals. It documents the progressive understanding that it is not only necessary to search, screen and understand signals, but also to assess and select them so as to distinguish between true, false and fake ones. The capability to process signals and transform them into actual information stems from the stock of competence and knowledge that individuals and organizations possess and mobilize. Together with an original introduction by the editor, this collection will be an indispensable research tool for economists and scholars alike.