Annotation

An annotation is a metadatum (e.g. a comment, explanation, presentational markup) attached to text, image, or other data. Often, annotations make reference to a specific part of the original data.

Textual scholarship is a discipline that often uses the technique of annotation to describe or add additional historical context to texts and physical documents.

Students often highlight passages in books in order to refer back to key phrases easily, or add marginalia to aid studying. One educational technique when analyzing prose literature is to have students or teachers circle the names of characters and put rectangular boxes around phrases identifying the setting of a given scene.

Annotated bibliographies add commentary on the relevance or quality of each source, in addition to the usual bibliographic information that merely identifies the source.

From a cognitive perspective annotation has an important role in learning and instruction. As part of guided noticing it involves highlighting, naming or labelling and commenting aspects of visual representations to help focus learners' attention on specific visual aspects. In other words, it means the assignment of typological representations (culturally meaningful categories), to topological representations (e.g. images). This is especially important when experts, such as medical doctors, interpret visualizations in detail and explain their interpretations to others, for example by means of digital technology. Here, annotation can be a way to establish common ground between interactants with different levels of knowledge. The value of annotation has been empirically confirmed, for example, in a study which shows that in computer-based teleconsultations the integration of image annotation and speech leads to significantly improved knowledge exchange compared with the use of images and speech without annotation.

Markup languages like XML and HTML annotate text in a way that is syntactically distinguishable from that text. They can be used to add information about the desired visual presentation, or machine-readable semantic information, as in the semantic web.

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