Glosses were originally notes made in the margin or between the lines of a text in a classical language; the meaning of a word or passage is explained by the gloss. As such, glosses vary in thoroughness and complexity, from simple marginal notations of words one reader found difficult or obscure, to interlinear translations of a text with cross references to similar passages. Today parenthetical explanations in scientific writing and technical writing are also often called glosses. Hyperlinks to a glossary sometimes supersede them.