If we want to know what she wrote about Joe Biden we have some very inefficient choices.
1. Read the whole book to find mentions of Biden.
2. Randomly flip through the pages.
3. Call up friends who have read the book to see if they remembered where he was discussed.
4. Google the book to see if anyone has created an index for the book.
Luckily, someone at slate.com created an index for her book.
All indexes are created the same way. An editor reads the book, comes up with a list of subjects, and gives pointers (page numbers for books, links for online sources) for each subject..