The most common and straightforward function of an annotated glossary is to define a word or phrase. Entries are arranged alphabetically to help you find the word you are searching for as quickly as possible. If the word is uncommon, or from a language different from the one in which the glossary is written, a pronunciation guide is often included.
A good annotated glossary will not only define terms, but enrich them with context and further explanation. For example, in the Puja Glossary and Pronunciation Guide of the Smithsonian Museum of Asian Art, the entry for "Nandi," the holy bull, provides not only a definition of his role as the mount of Shiva, but also what he represents in Hindu culture: "strength, faith and constancy in belief."
Particularly in topic-specific annotated glossaries, an entry will often provide a definition and then redirect you to a similar or supporting entry that can supplement its information. In the "Annotated Glossary of Amateur Astronomy Acronyms and Terms," the term "light year" is defined as "the distance light travels in one year," and is accompanied by an exact measurement of kilometers per second and tips on understanding and measuring such distances. It closes with the note "see Quasar," redirecting you to an entry which involves the practical implementation of light years, a useful side note to help you determine the definition and function of light years.
Annotated glossaries come in all shapes and sizes, and can accommodate a wide range of topics. Academic and scholarly books of all fields will frequently include an annotated glossary to support and define their research. Stand-alone annotated glossaries can also be found online for almost any subject, including business, science, entertainment, education and technology.