Too Long; Didn't Read
What does <a href="http://buffer.com" target="_blank">Buffer</a>, <a href="https://new.chooseblocks.com/discover/overview" target="_blank">Blocks smartwatches</a>, and <a href="http://www.producthunt.com/" target="_blank">Product Hunt</a> have in common? They started gaining traction by tweeting to people.