In applied linguistics, an error is an unintended deviation from the immanent rules of a language variety made by a second language learner. Such errors result from the learner's lack of knowledge of the correct rules of the target language variety.[1] A significant distinction is generally made[by whom?] between errors (systematic deviations) and mistakes (speech performance errors) which are not treated the same from a linguistic viewpoint. The study of learners' errors has been the main area of investigation by linguists in the history of second-language acquisition research.[2]
In prescriptivist contexts, the terms "error" and "mistake" are also used to describe usages that are considered non-standard or otherwise discouraged normatively.[3] Such usages, however, would not be considered true errors by the majority of linguistic scholars.[4][5] Modern linguistics generally does not make such judgments about regularly occurring native speech, rejecting the idea of linguistic correctness as scientifically untenable,[6] or at least approaching the concept of correct usage in relative terms.[7] Social perceptions and value claims about different speech varieties, although common socially, are not normally supported by linguistics.[8]