Snapchat have update their app to include Snap Maps, a location tool that allows users to view the location of other Snapchat users.  The app opts in to this automatically if you follow the ‘what’s new’ feed and therefore, to prevent people from knowing where you are, you need to opt out.  This is called Ghost Mode.

Please see the videos on YouTube that explain more about the update and what you can do to keep yourself and others safe.