As others have said above, the "right" answer to this is to parse the HTML. Unless the HTML is malformed, you'll be able to reliably extract titles.

The "pragmatic" answer may be different. 99.9+% of the time, extracting a title using a regex works just fine. It's not the bullet-proof way, but in my experience you'll see far fewer real problems than you'll see theoretical ones. If you're not sensitive to the risk, and want to avoid taking on the overhead of using a parser,

  if ( $html =~ m|<title>(.*?)</title>|is ) {
      $title = $1;
  } else {
      # note that you failed to find a title
  }
[download]

will work just fine. You may still need to strip leading or trailing whitespace, and convert any newlines to spaces.

If you're extracting much more that the title, though, I'd go with a parser.