Applied linguistics uses knowledge about language, its acquisition and use to solve real-world problems. Traditional areas of focus include second language acquisition theory, pedagogy and their interface. Other areas are authorship identification, forensic linguistics, and language disorders. Applied linguistics has expanded to include language and its relation to assessment, the brain, cognition, culture, ideology, instruction, interaction, media, policy, reading, research methodology, society, speaking, technology, translation and writing. The field has developed from a focus on discrete language elements to more holistic perspectives considering social and contextual factors.