Perl's lc() function takes a string, makes the entire thing lowercase, and then returns the new string.
$STRING = lc($STRING);
First, $myWord is set to a value of 'WORD', then the lc() function is run on $myWord. The lc() function takes the entire string $myWord and converts it to it's lowercase equivalent. The value of $myLowerWord is then equal to 'word'.
$myWord = 'WORD'; $myLowerWord = lc($myWord);