Definition of Second Language Acquistion

Second Language Acquisition (SLA) is the study of how second languages are learned. In other words, it is the study of the acquisition of a non-primary language; that is the acquisition of a language beyond the native language. It is the study of how learners create a new language system with only limited exposure to a second language. It is the study of what is learned of a second language and what is not learned; it is the study of why most second language learners do not achieve the same degree of knowledge and proficiency in a second language as they do in their native language; it is also the study of why only some learners appear to achieve native-like proficiency in more than one language. Additionally, second language acquisition is concerned with the nature of the hypotheses (whether conscious or unconscious) that learners come up with regarding the rules of the second language.
The study of second language acquisition draws from and impacts many other areas of study, among them linguistics, psychology, psycholinguistics, sociology, sociolinguistics, discourse analysis, conversational analysis, and education, and so on. That’s why second language acquisition is truly an interdisciplinary field.