A glossary is used to look up a definition of a word or phrase.
An index is used to find where a word or phrase was used in a book, by page number.
A list of items that will be mentioned in a book is a table of contents, these are organized by sections, pages, or chapters.
A word or brief sentence telling what the chapter or article will be about.
All of these will help you find references to specific concepts in a text.
