What is "mail merge?"
Mail merges take information from an outside data source, and merge it with a Word document. It's a great way to create form letters or labels with very little work.
For instance, you might use a mail merge to plug different names and addresses into the same basic form letter, creating a custom-addressed letter for hundreds of people.
The mail merge might get names and addresses from a Microsoft Access database.
It could get them from Word document, with all the names and addresses stored in a table.
It could get them from a Microsoft Outlook address book, or even a Microsoft Excel spreadsheet.