Formation, development and institutionalization of digital economy (DE) is in its third year now in the Russian Federation. However, there is still no comprehensive understanding of DE in foreign or Russian economic science, and no fundamental studies have been carried out on digital economy’s relationship with the analog and real economies. The goal of this article is to gain further insight into the phenomenon and analyze the results of the fourth information revolution (using Peter Drucker’s definition) and the fourth industrial revolution (using Klaus Schwab’s definition), institutional environment of digital economy, and, ultimately, the digital segment of the real economy. The study presents the theoretical and practical fundamentals of analog, real and digital economies, refining their definitions. Digital economy, or, rather digital information economy, is represented in the context of a new type of mixed economy, analog-to-digital; this concept is introduced for the very first time. Information, or, more precisely, energy and information, technological and production know-how are considered as the main resource of the digital economy. Original appraised interpretation is provided for DE as an emerging system (and possibly antisystem) of production and/or economic relations that can function without direct human participation «in the field of production as Industry 4.0 (cyber systems together with the «Internet of Everything»), virtual distribution, exchange via digital platforms and individualized consumption as the main phase of reproduction of information goods» in digital form. Technological essence, parameters in the form of digital technologies and the role of digital economy as a digital segment of the real economy have been defined. The new practically important results obtained in the study are the correlation between the digital sector and the real economy, exceeding economic growth rates of DE compared to those of analog economy at the present time. Viability of the analog economy is demonstrated in contrast to speculations on the «demise of analog economy» (discussed at the Information Technology of Industrial Russia conference). Interaction and direct correlation of analog and digital economies have been revealed.