What is applied linguistics?

"Applied Linguistics is an interdisciplinary field of inquiry that addresses a broad range of language-related issues in order to improve the lives of individuals and conditions in society. It draws on a wide range of theoretical, methodological, and educational approaches from various disciplines–from the humanities to the social, cognitive, medical, and natural sciences–as it develops its own knowledge-base about language, its users and uses, and their underlying social and material conditions."

–The definition of applied linguistics by the American Association for Applied Linguistics.