A corpus contains special additional information about the properties of the texts included in it (so-called markup, or annotation). The presence of annotation is the main characteristic of a text corpus that distinguishes it from simple collections (or “libraries”) of texts.

The richness and variety of annotation ensure the corpus’s scientific and educational value. At present, the following types of annotation are used in the Russian National Corpus: morphological annotation; annotation of word-formation structure (morphemic composition); syntactic annotation; semantic annotation; lexico-functional annotation; ellipsis annotation; microsyntactic annotation; coreference annotation; temporal annotation; and meta-annotation (text parameters).