The article discusses location-based services and mobile advertising. It is noted that multiple business models can be used, some of which are thought to have the potential to generate billions of dollars. However, significant challenges are also noted, both in terms of technical implementation and business planning. Location tracking systems and wireless internet technologies such as Bluetooth, RFID (radio frequency identification systems) and GPS (Global Positioning System) are discussed, in the context of online advertising for smartphones or tablet computers.