Glosses are many kinds of attempts to supply what is perceived to be deficient in a reader's procedural or declarative knowledge.

According to Hüllen (1989), glosses were once of three types: synonyms, encyclopedic comments, and grammatical notes.

Blohm (1982) coined the term gloss paraphrase, which he defined as "a type of reader-activated superimposed intratext notation that replaces abstractly-composed text content with concrete referents to promote readers' cognition".

More examples of a gloss "by any other name" are: adjunct aids (Otto & White, 1982), metanotes (Wolfe, 1990), metatext (Lantolf, Labarca, & den Tuinder, 1985), and paratext (Genette, 1987). Oxford (1995) provides many possibilities under the rubric of assistance: "error correction... a useful learning strategy... a full explanation, a schematic/partial explanation... a leading question... a pictorial representation of a verbal expression... a cooperative learning activity... an encouraging word at just the right moment".

Electronic glosses can take many forms. Online (hyper) glosses can be in the form of video, sound, or pictures. Icons, a type of picture, have also been used as glosses.