Annotation

Noun

 * 1) a critical or explanatory commentary or analysis
 * 2) a comment added to a text
 * 3) the process of writing such comment or commentary
 * 4)  metadata added to a document or program
 * 5)  information relating to the genetic structure of sequences of bases

Thesaurus
adversaria; aide-memoire; apparatus criticus; comment; commentary; commentation; docket; entry; exegesis; footnote; gloss; item; jotting; marginal note; marginalia; memo; memoir; memorandum; memorial; minutes; notation; note; note of explanation; register; registry; reminder; scholia; scholium; word of explanation