Defining Sort Criteria Can add an anonymous subroutine block to customize sort order @sorted_nums = sort { $a <=> $b } @nums # @nums has 1 .. 10; Perl puts two of the values from the list into $a and $b Block compares values and returns -1, 0 or 1 0 means $a and $b are identical -1 means $b comes first 1 means $a comes first <=> does this for numbers cmp for strings