Contemporary society, the society of the future, will require us to develop entirely new knowledge, skills and competences. In this respect, functional literacies are among the key competences for the 21st century society, which is known in Japan as Society 5.0, or the so-called super-smart society. The qualitative leap from Society 3.0, the industrial society, to Society 4.0, known also as the information society, has already been marked by computers and their processing power in the form of virtually unlimited memory capacity. Humans as intelligent beings, on the other hand, have made little progress over the last few centuries in terms of information processing power and storage capacity. The shift to a super-smart society, i.e., Society 5.0, can hardly be imagined with just humans as the central characters in these changes, given their limited processing power and memory capacity. The society of the future, the super-smart society, is surely going to be a technological society, a society of independent and smart systems, which are going to be managed and directed more or less by artificial intelligence (AI), because this is the only way to arrive to the so-called super-smart society. In such an environment it will be vital for humans, who will be increasingly dependent on technology, not only to be able to communicate with their equals, i.e., other humans, but also to be able to understand technology and AI, and communicate with it in some way or another. This book focuses on literacy for the 21st century and/or Society 5.0 in the narrow sense. In other words, the focus is on the reading, writing and communication processes as part of digital literacy, or, indeed, as part of the digital, technological and engineering literacy 4.0/5.0 paradigm. The latter includes competences required for the three main ways of communication in the 21st century, which are: human-human communication via the Internet of Things (IoT) or/and the Internet of People (IoP); human-machine communication, directly and via the IoT; communication between humans and artificial intelligence (AI). In these three types of communication, humans will be expected to apply particular ways of thinking and reasoning when addressing a problem, and to acquire and demonstrate three kinds of practices/skills in particular: understanding technological principles; developing solutions and achieving goals and communicating and collaborating. The main topics in this book are organized into nine core chapters, including the following: Development of Human Society and the Function of Communication Skills and Media, Historical Development of Communication Media, Literacy and Artificial Intelligence, and The Direction of Society's Development in the 21st Century. It seems fair to assume that some of the explanations, points of view and parts of content presented in this book will be different from notions generally true. We hope that because of this, we will be able to provoke cognitive dissonance/intellectual unease in the reader, thus encouraging them to update and/or internalize some of the "theories inside their heads", which have been embedded there since their school years.