4. Variable name delimiter 

my $str = "The tip top pot pit";

if($str =~ /t.*p/p) {
    say "Prematch:  '${^PREMATCH}'";  # 'The '
    say "Match:     '${^MATCH}'";     # 'tip top pot p'
    say "Postmatch: '${^POSTMATCH}'"; # 'it'
}