Mike Sharwood Smith coined the term to cover techniques used by researchers to make salient selected features of a language for students such as word order, parts of words that express tense, agreement and number for example, accents, idioms and slang.
[1][2] These techniques aim to draw attention to aspects of a language that have hitherto seemed to have made insufficient impact on the learner.
This need not necessarily involve making learners consciously aware of the researcher's or teacher's intentions.
Although IE was conceived of as a research tool, the term can also be used to describe techniques deliberately or instinctively used in language teaching and also in the way parents (again instinctively) talk to their children as also the way people alter their speech when talking to non-native speakers who seem to have difficulty in communicating.
Sharwood Smith distinguishes external input enhancement from internal input enhancement with the former referring primarily to techniques used in the deliberate teaching of a language and the latter employing ordinary events or situations.