An index is a list of words or phrases, along with their corresponding page numbers, that appears at the end of a book or document. The purpose of an index is to allow readers to easily locate specific information within the book or document.

    An index is typically organized alphabetically, with each entry consisting of a word or phrase followed by the page numbers on which it appears. Some indexes also include cross-references, which are references to related words or phrases that appear elsewhere in the index.

    Indexes are commonly found in non-fiction books and other documents that contain a large amount of information, such as textbooks, encyclopedias, and technical manuals. They are an essential tool for helping readers quickly locate specific information within a document and are an important part of the overall organization and structure of the document.