Your headline is the first, and perhaps only, impression you make on a prospective reader. Without a headline or post title that turns a browser into a reader, the rest of your words may as well not even exist.
But a headline can do more than simply grab attention. A great headline can also communicate a full message to its intended audience, and it absolutely must lure the reader into your body text.
At its essence, a compelling headline must promise some kind of benefit or reward for the reader, in trade for the valuable time it takes to read more.