Applied linguistics is the interdisciplinary study of language and its applications in real world contexts. It draws on linguistic theories and research to solve practical language-related problems. Key areas include second language acquisition, teaching methodology, testing, and the relationships between language and society, technology, and other fields. Throughout the 20th century, applied linguistics influenced the development of language teaching methods, shifting the focus from grammar translation to more communicative, meaning-based approaches grounded in theories of language acquisition and use.