A navigation system used inside venues such as airports, museums, shopping malls and hospitals. An indoor positioning system (IPS) is the indoor counterpart to the global positioning system (see GPS). In the past, a variety of communications methods have been used, including optical and acoustic; however, now that so many people have smartphones with Wi-Fi, the mobile app has become the viable approach. Navigation Plus Information A feature of an indoor positioning system is not only directions but also the information that can be retrieved. For example, passing by a store in a mall can trigger the day's specials on a smartphone app. In a museum, more facts can be displayed as the visitor approaches an exhibit.