EN
English as a Lingua Franca (ELF) is a sociolinguistic phenomenon of the 21st century. ELF enters the intercultural communication on a daily basis and is an indisputable part of our sociolinguistic reality. The ultimate aim of this article is to provide a complex theoretical basis for further empirical studies in any of the linguistic fields connected to ELF. In doing so, it gives a diachronic overview of the development of ELF starting with the origins of its name, through the current situation up to its future prognosis. Moreover, the presented article is predominately focused on the description of the following areas: the conceptualisation of ELF; the phonological, lexico-grammatical and pragmatic features of ELF; its possible application into the field of language teaching; the insights into the area of translation and interpreting; and its close relation with corpus linguistics. Last but not least, this paper demonstrates the significance of the study of ELF for the future linguistic development.