What is the importance of merge mail in word processor?

In Microsoft Word, or any Word processor, mail merge is one of the most powerful features. It enables you to create multiple versions of a letter or document, enabling users to create circulars which can be personalised. So a letter that you want to send to 100 different people, each with their own name on it, can be done by typing the letter just once, and put each different name into each letter. You merge the list of names with the letter to come up with multiple versions, saving you huge amounts of time.