Perl code doesn't *have* to be written in a particular format or style, at least regarding indentation or (sometimes) your choice of delimiters (c.f my @array = qw/1 2 3/ or my @array = qw(1 2 3) etc...).

However there is a certain 'style' that is encouraged, to help your code be readable and organised, and sometimes to encourage good habits. This is much better explained and detailed in perlstyle.

For examples of how far you can get from this and still produce working code see Obfuscated code!