It occurs at the conclusion of the book or document and contains specific words, pages, and themes from the material. A table of contents is a list of the sections of a book or document, whereas an index is a list of key words, concepts, and other relevant information in a book or document. The term "index" comes from the old English word "indicium," which means "a point of reference or direction." As such, an index can be considered a guide or map for your reader to find what he or she is looking for. An index may be a separate work inserted into the main text or it may appear at the end of the volume. If it appears at the end, then it is called an appendix. Although a separate work, an index often includes only a few paragraphs for each entry; this is because writers tend to use abbreviations and acronyms when writing about books or documents themselves. So rather than repeat lengthy terms when referencing back to those works, they are usually given as indices. The goal of an index is to make finding certain topics in a book or document easy. This helps readers who want to look up something quickly without having to read through everything else first. Indexes are also useful for writers who do not have time to fully describe every topic within their works but still want to provide sufficient information for others to understand them. By including only important terms when creating an index, writers can include more content in less space!