about_testdrive.help.txt

Plain text file Reference

A .txt file contains plain text without formatting. Any text editor can open, show, and change the file. The content has no fixed structure, only characters and line breaks. Common uses are notes, logs, and documentation such as readme files. The encoding is frequently UTF-8, but older files can use other encodings.

A file extension is only a part of the file name. It does not give a guarantee about the format or the content of a file. But on Windows, the extension selects the program that opens the file.