Well, I know that it commonly refers to "End Of File" (and that some languages treat it as a reserved word because it is used as such, but QBASIC does not, so I use it to store the string that is to be found at the end of the data file, so that I can compare the latest input from a file with that to see if I've reached the end of the file, since i could use the QBASIC function that allows you to check for the end of a file, but it's alwas out by one either way (either it reads 1 line more than there actually is, and crashes, or reads 1 line too few and misses the last data out) That's why I structure my data files with a start and end "tag", and for convenience, and because it's fairly recognisable, I use a HTML style "tag":

<Program Name>

...
...
...

</Program Name>

And the eof$ = "</Program Name>" is just to store the value of the end tag so that I can compare it each time with the input that's just been read from the file, and see if I've reached the end of the file without relying on QBASICs EOF function which seeps to have a fencepost error somewhere along the way!!