<Handle> for an input file means "read the next line from that file".

E.g.    $line = <STDIN>;

... stores the next line from standard input in the variable $line.

Output file handles are used as the first argument to the print command.

E.g.    print REPORT "Report for $today\n";

... writes a line to the file attached to the REPORT handle.

Note: no comma after the handle ID