indexed - technical definition

Refers to words that are turned into a list of words and pointers. When an individual book or document is indexed, important words and word phrases are determined and made into a keyword list. That list is matched against all the pages. When there is a match, that page number is added to the appropriate word or word phrase in the keyword list, which is sorted alphabetically and placed at the end of the book or document.

When multiple documents are indexed as a group, all important words on every page wind up as pointers to those documents in indexes for that word or word phrase. For example, if document abc.doc contains the word "computer," abc.doc is added to the "computer" index. For general documents, keyword lists are generally exclusionary, which means every word is indexed except for numerous common words such as "and," "the," "this," "to," "for" and "that."