Looking back at the last decade, the mobile phone has been greatly developed from only voice call and text message to a multi-purpose device, including camera, music player, games, and even small computer. The development of internet features in mobile phones has also continuously and...

Over millennia, mankind has used hard cash in various forms ranging from shells to gold coins and paper. More recently, cash has become unpopular in political circles, as it effectively restricts states’ power to tax (explicitly or via negative interest rates) or to survey and potentially...