The declaration of main looks like this:

int main();

This indicates that main is a function returning an integer. In hosted environments such as DOS or UNIX, this value or exit status is passed back to the command line interpreter.

 Under UNIX, for example, the exit status is used to indicate that a
program completed successfully (a zero value) or some error occurred
(a non-zero value).

The Standard has adopted this convention; exit(0) is used to return
‘success’ to its host environment, any other value is used to
indicate failure.

If the host environment itself uses a different numbering
convention, exit will do the necessary translation. Since the
translation is implementation-defined, it is now considered better
practice to use the values defined in ****<stdlib.h>****:
EXIT_SUCCESS and EXIT_FAILURE.

So writing int main() is a good practice .Void could be used but it is better to use it for functions other than main()