Help:Annotation

Annotation is the process of text editing in which the editor tries to give more information about a specific text fragment or a word, making an annotation.
E.g. in an hypothetical letter written by Roberto Bellarmino to Claudio Acquaviva in 1599, we could find a text like this

Thanks for your letter and bring my greetings to the Pope.

This text brings two pieces of information:

1. the existence of a letter sent by Acquaviva to Bellarmino before this one
2. the reference to a not better specified 'Pope'

To help the readers to undestand the text, in a traditional printed edition the editor would add a footnote to outline his knowledge about these points.