According to the Linguistic Society of America, Applied Linguistics refers to "to a broad range of activities which involve solving some language-related problem or addressing some language-related concern" whereas Linguistics is "is the scientific study of language." Applied linguistics uses the knowledge and theories of linguistics within inter-disciplinary, real world situations such as in research methodology, discourse analysis, language policy, interpreting, language testing, etc.
Many different disciplines, such as psychology, anthropology, communication, media studies, etc., use linguistic knowledge or contribute themselves to the field of linguistics. Applied Linguistics bridges the gap between these fields and Linguistics. For instance, Applied Linguistics would study the use of language to influence others within Psychology. Within Politics, Applied Linguistics would the study the rhetoric politicians use to inspire their constituents or to interpret foreign language. In Ethnography, Sociology, and/or Anthropology, Applied Linguistics can help ensure that research methodology remains unbiased or does not influence those surveyed or researched.