What3words: the app that could save your life

What3words is a free app that points to a very specific location in the world.  It has divided the world into 57 trillion squares, each measuring 3m by 3m (10ft by 10ft) and each having a unique, randomly assigned three-word address.  When you download the app it will find your location and give you the 3 words that are assigned to your location – which can be given to emergency services to enable them to locate you straight away.  The app does not need a phone connection to give you your three words.