Annotation

n. comment or explanation added to a text; comment or remark added to a computerized document (Computers); additional information about a part or feature of a computer program (Computers)

Annotation is extra information asserted with a particular point in a document or other piece of information.Most commonly this is used, for example, in draft documents, where another reader has written notes about the quality of a document at a certain point, "in the margin".Annotations about bibliographical sources, labeled annotated bibliographies, give descriptions about how each source is useful to an author in constructing a paper or argument. Creating these blurbs, usually a few sentences long, establishes a summary for and expresses the relevance of each source prior to writing.
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Noun
1. a comment or instruction (usually added); "his notes were appended at the end of the article"; "he added a short notation to the address on the envelope"
(synonym) note, notation
(hypernym) comment, commentary
(hyponym) poste restante
(derivation) annotate, footnote
2. the act of adding notes
(synonym) annotating
(hypernym) expansion, expanding upon
(derivation) annotate, footnote

n. annotation, note

(n.)
A note, added by way of comment, or explanation; -- usually in the plural; as, annotations on ancient authors, or on a word or a passage.