What is a \'.txt\' file extension on a Macintosh?
When a user on a Macintosh sees a file with a .txt extension, this indicates that the file is a plain text file. These can be opened and edited with a variety of programs, including simple text editors like TextEdit on macOS, or more complex word processing programs. The .txt extension is quite universal and signifies that the file contains unformatted text.
It is not specifically indicative of an app needing to perform additional actions, package contents being copied, applications being sideloaded, or an app being installed.