Final answer:
To perform a mail merge, you need two essential data files: the main document and the data source. The main document serves as a template, while the data source contains individual recipient data to be merged.
Step-by-step explanation:
To perform a mail merge, you only need two data files. The first is the main document, which is the template that will be used to generate all the personalized instances of the document, such as a letter, email, or label. The second essential file is the data source, which contains all the personalized information that will be merged into the main document, like names, addresses, or any other relevant details.
The process involves linking these two files in a mail merge software or tool, where the data source is merged into the main document, creating multiple personalized copies of the main document, each containing different information from the data source file.