Book excerpt: Experts know that multilingualism is not the so-called minority phenomenon as many people think it to be. Although it is difficult to provide the exact statistical data on the multilingual speakers and distribution of multilingualism in the world, sociolinguists and linguists estimate that there are roughly around 6000 languages in the world. The focus of this book chapter is to succinctly present the sociolinguistic aspects of language choice and use of multilingual speakers in various domains. Besides, concepts such as bilingualism and multilingualism and their dynamics in the field of sociolinguistics have been critically been reviewed and presented from the theoretical and empirical perspectives. Further, some of the relevant issues related to language choice and use in multilingual speech communities in different parts of the globe are reviewed and included. Furthermore, factors inducing multilingualism among different speech communities and individuals have been reviewed and finally, recent developments and dynamics toward the spread of multilingualism in various parts of the world are also presented in the chapter.