What is an 'index' commonly found at the end of a book?

An index is designed to serve as an alphabetical list of topics, names, and subjects found in the text, along with page numbers that reference where those items occur throughout the book. This allows readers to quickly locate specific information without having to read through the entire book.

For example, if a reader is looking for information on a particular character or event, they can consult the index to find the exact pages on which those topics are discussed. This feature is particularly useful in non-fiction and academic texts, where readers often need to pinpoint specific facts or discussions.

The other options, while potentially found in books, serve different purposes. A summary of chapters condenses the content of each chapter but does not provide a quick reference for locating specific information. A glossary explains terms used in the text, which is helpful for understanding vocabulary but doesn't assist in finding specific references like an index does. A list of characters may give an overview of personalities within the story, but again, it does not offer the detailed references found in an index.