This textbook is dedicated to multilingualism, the social and individual language practice that has come to the fore in today's human society, and which is the focus of this textbook. The various aspects of multilingualism relate to spheres as diverse as human physiology, cognition, communities and their traditions and material objects, and, of course, languages. Multilingualism concerns education, engineering and commerce, policy-making, family life and entertainment, to name only some of its dimensions, but it cannot be reduced or equated to discrete disciplines of sociology, psychology, cultural studies or linguistics. Despite such a diversity of facets, every-thing in the realm of multilingualism invariably boils down to one of its three basic constituents – language, user and environment – or, rather, to their interaction. The result of this unique and complex interplay is manifested in the practices of multilingualism, so exciting and so enticing to understand.

The field of multilingualism is not entirely new; numerous books and articles treat it from a variety of angles, some representing it geographically and politically, others focusing on educational and social aspects, or exploring the identity of multilinguals in depth (see, for example, Pattanayak 1990; Todeva and Cenoz 2009; Rindler-Schjerve and Vetter 2012; Phipps 2019; Banda 2020). In addition, there are not that many books to date that provide a general and systematic understanding of the entire field of multilingualism. This textbook is intended to fill this gap and to demonstrate how the multiple dimensions of multilingualism work in concert, constituting the complex reality that we encounter today.

Usually, students of various specialisations such as linguistics, sociology or pedagogy are taught only selected issues inherent in multilingualism, closely linked to the specific interests of each discipline. For example, out of all possible multilingualism content, students of sociology and political science are offered topics related to minority and language rights, identities in post-colonial societies, and indigenous languages. These students are less likely to be exposed to the issues of teaching second and third languages, unlike those studying education and pedagogy. To balance and complete the expertise, this textbook offers a panoramic perspective on multilingualism and provides students in various fields of learning with a basic introduction to both classic and current issues of using and learning multiple languages.