 Linguistic annotation

Linguistic annotation adds explicit analytical information to language data, such as word boundaries, part of speech, grammatical number or syntactic dependencies. The original text and the assigned labels are distinct: an annotation records an analysis under stated conventions, rather than being an uninterpreted observation.

In the sentence Birds fly, one analysis assigns the lemma forms bird and fly, the categories noun and verb, and a subject relationship connecting the first word to the second. Universal Dependencies represents such information in CoNLL-U, separating word forms, lemma forms, grammatical features and dependency fields.^[ref]

Keeping those layers separate permits a revised grammatical analysis without silently changing the underlying recording. It also makes disagreement inspectable: two annotators may agree on the text but assign different categories. A reusable annotated text corpus therefore needs its conventions and ambiguous cases documented alongside the labels.