Despite the history of mobile smartphones being relatively recent, it is nonetheless already littered with a trail of failed operating systems. From BlackBerry OS to Windows Phone to WebOS, a number of them came and went before the market calcified into two dominant players: Android and Apple. And according to Bill Gates, his biggest mistake at Microsoft has been missing the boat in the mobile OS wars. Perhaps no company is as synonymous with desktop operating systems as Microsoft, but the software giant has now all but conceded the mobile marketplace to others. It just goes to show you that in tech, even the biggest companies can get left in the wake of fast-moving innovation.