Now five years old, Facebook has more than 150-million users worldwide, and its founder, Mark Zuckerberg, is rated by Forbes as the 321st richest person in the world. Not bad going for a college dropout.But aside from Zuckerberg’s prodigious business acumen, what has been the secret of Facebook’s popularity?Those who doubt its value to humanity will frequently ask, “well, OK, what does it do?”; answering that question concisely and coherently is surprisingly difficult. Read the full article here…(Image credit: “Scott Beale / Laughing Squid” http://laughingsquid.com.)