Computers are useful tools to help with creating an index however a computer doesn't have the ability to evaluate context. They are not able to discern subtleties of word usage, the importance of concepts relative to the book’s topic and homonyms. They aren’t able to think like a reader and choose terminology or make decisions to create cross references for those who may be looking up a similar word. When faced with space limitations and the need to edit, computers aren’t able to decide which headings should be combined under a new heading. Collecting the information to index, that is, the concept and corresponding page numbers is only one part of indexing, the other is structuring the index and that requires contextual information and a human being knowledgable about the subject matter to make decisions.