This book offers an introduction to the many facets of multilingualism in a changing world. It begins with an overview of the multiplicity of human languages and their geographic distribution, before moving on to the key question of what multilingualism actually is and what is understood by terms such as 'mother tongue', 'native speaker', and 'speech community'. In the chapters that follow, Florian Coulmas systematically explores multilingualism with respect to the individual, institutions, cities, nations, and cyberspace. In each of these domains, the dynamics of language choice are...