The economics of information. Theory and practice is an English-language version of the monograph Ekonomia informacji written in September 2019 and published at the beginning of 2020. The idea of translating it into English was born after posting the texts on Research-Gate. Then requests to make it available in English appeared. Rapid changes that have taken place in the world economy over the past year caused some authors to consider it necessary to include them in their texts. Therefore, the update of the texts have been provided, mainly in the context of consequences of the pandemic, but also concerning the entry of Brexit into the next phase. Attention was paid not only to the theoretical but most of all to the practical dimension of information economics. Moreover, the comments that appeared in reviews published in scientific journals, including those concerning the structure of work, have been taken into account. The monograph consists of eight chapters. Each of them was written by a different author. In the first chapter, the conceptualization of the term ‘economics of information’ was presented. It covers the genesis of information economics, an original definition and methodological foundations. It is a starting point and supporting structure of the entire book. The authors of the remaining chapters refer to and comply with the adopted convention of analysis presented by the research editor. The second chapter is devoted to the economics of information in internal communication in the era of social media. It constitutes a sort of bridge between information economics and public relations narrowed down to internal communication. Jacek Trębecki refers to the relationship between behavioral economics and classical economics. He emphasizes that the consequence of information asymmetry may be its influence on distortion of decisions. Chapter three by Waldemar Rydzak – Changes in Access to Information in Crisis Situations – as intended by the author, is to be a starting point for a discussion about the role of information in the contemporary market, which is more and more frequently discussed in the context of the fourth digital wave of development, with significant influence of mass media and the Internet, also in the context of the COVID-related situation. In the fourth chapter, Filip Kaczmarek used the assumptions of counterfactual analysis in his considerations, and on the basis of its results he showed that the so-called opportunity costs, or ‘cost of non-Europe’, are used as an instrument of legitimizing the European Union. In chapter five by Aleksandra Rabczun, Brexit and the Economics of Information, the Brexit case was analyzed in the context of the role played by information economics in this process. Chapter six, written by Izabela Janicka, is an example of using the concept of economics of information to analyze one country, in this case Germany. It was also assumed that both macro and micro aspects are taken into account. The author points to the overriding role of information in the post-industrial economy and to the fact that information has become one of the basic production factors. She also introduces the concept of a functional information minimum and an information gap. In the seventh chapter Marcin Leszczyński defines the role of the state’s reputation in reducing information asymmetry in the global market. The chapter ends with the analysis of policy and diplomacy in shaping trust in a government and the demand for products from a given country on the example of the trade war between the US and China. In the eighth chapter, Information, Welfare and Migrations – Practical Remarks in the Context of the Economics of Information, Katarzyna Świerczyńska fitted into the scope of research on the impact of information on economy and economic decisions of entities at the mega-economic level.