# Which tool to use: an index or a glossary?

I have this situation:

• My book needs an alphabetical index, used for finding on which page an item appeared.
• My book needs a glossary, used for looking up the definition of the item.
• Every indexed items will appear in the glossary and vice versa.
• I need something compact, but easy to read.

Therefore, it seems fitting that there should only be one section to refer to in the back, either an index (with definitions) or a glossary (which serves as an index). Which would be the best way to go? Is there another choice?

Do publishers ever combine the glossary and index into one section? What do they call it?

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A glossary may include not only definitions of certain items, but also (like an index) indicate the page(s) where these items appeared. If, in addition, every indexed item (and not only a subset) also appears in the glossary, a separate index is superfluous.

Here's an example of a (hopefully) "compact, but easy to read" glossary produced with help of the glossaries package. You may also use the hyperref package (which, unlike with most others packages, must be loaded before glossaries) to add hyperlinks in the glossary as well as in the main text body.

\documentclass{article}

\usepackage{hyperref}

\usepackage{glossaries}
\makeglossaries

\newglossaryentry{electrolyte}{name=electrolyte,%
description={solution able to conduct electric current}}

\textheight=80pt% just for the example

\begin{document}