The linguistics of English
The mechanisms of speaking and understanding the language
Everything we think or say to ourselves or to one or more others, with some sort of expression which may remain entirely within our minds, with some meaning is defined by linguistics – in the case of English, the linguistics of English.
Language may involve one person talking to one or more other people. But this is not necessarily so. Someone with a profoundly disabling condition, utterly unable to form even one comprehensible word, can yet conceive of meaningful sentences of exactly the same complexity as an able-bodied speakcr. The universality is in the fact that a sentence is meaningful rather than that it is actually uttered.