Second Language Acquisition, world Englishes, and English as a Lingua Franca (ELF)

English as a Lingua Franca (ELF) is a complex form of language contact, which is viewed from three key perspectives: the cognitive, the micro‐social /interactional, and the macro‐social. Each contributes crucially to the whole, and each frame has its own dynamics, while feeding into the other levels. Each operates in its particular time scale, resulting in multiple synchronous and asynchronous processes of change. As a contact language, ELF embodies second language use (SLU), which is distinct from Second Language Acquisition (SLA). We can expect ELF to have affinities with world Englishes (WE), and there are indications that ELF is closer to WE than to SLA. English as a Lingua Franca provides unique insights for understanding second languages, on account of its global diffusion and its multiplex contacts with other languages.