Final answer:
Indexing a document involves attaching an identifying mark or phrase to it for efficient filing and retrieval.
Step-by-step explanation:
When you put an identifying mark or phrase on a document to ensure that it is properly filed, you are indexing it. Indexing is a crucial step in document management and archiving, allowing for easy retrieval of documents. By assigning a keyword, number, or other identifier, the content loaded in the document can be organized in a system that enhances the efficiency of filing and locating documents. This practice is common in business, legal, and medical offices where managing large volumes of paperwork is essential.