Second-language Acquisition

Second-language acquisition or second-language learning is the process by which people learn a second language. Second-language acquisition (often abbreviated to SLA) also refers to the scientific discipline devoted to studying that process. Second language refers to any language learned in addition to a person's first language; although the concept is named second-language acquisition, it can also incorporate the learning of third, fourth, or subsequent languages. Second-language acquisition refers to what learners do; it does not refer to practices in language teaching.

The academic discipline of second-language acquisition is a subdiscipline of applied linguistics. It is broad-based and relatively new. As well as the various branches of linguistics, second-language acquisition is also closely related to psychology, cognitive psychology, and education. To separate the academic discipline from the learning process itself, the terms second-language acquisition research, second-language studies, and second-language acquisition studies are also used. SLA research began as an interdisciplinary field, and because of this it is difficult to identify a precise starting date. However, it does appear to have developed a great deal since the mid-1960s. The term acquisition was originally used to emphasize the subconscious nature of the learning process, but in recent years learning and acquisition have become largely synonymous.

Second-language acquisition can incorporate heritage language learning, but it does not usually incorporate bilingualism. Most SLA researchers see bilingualism as being the end result of learning a language, not the process itself, and see the term as referring to native-like fluency. Writers in fields such as education and psychology, however, often use bilingualism loosely to refer to all forms of multilingualism. Second-language acquisition is also not to be contrasted with the acquisition of a foreign language; rather, the learning of second languages and the learning of foreign languages involve the same fundamental processes in different situations..

There has been much debate about exactly how language is learned, and many issues are still unresolved. There are many theories of second-language acquisition, but none are accepted as a complete explanation by all SLA researchers. Due to the interdisciplinary nature of the field of second-language acquisition, this is not expected to happen in the foreseeable future.