Wireless communication products take many different forms these days. Originally developed in the nineteenth century using radio waves only, wireless communication devices now function within a wide variety of applications, not just carrying voice communications from one place to another. Nowadays computer interface devices use cellular networks, and other forms of technology previously allocated for voice use only, as a means of transferring data. Wireless technology of many kinds is built into devices designed for both the consumer and professional markets. It is to be found in anything from industrial cleaning units to simple consumer items such as audio amplifiers. Wireless communication is also often found being applied in the healthcare sector in devices such as heart rate monitors. In the field of office and home computing, many devices use WLAN technology in order to network with one another locally in a wireless set up. GPS technology is also used in satellite navigation systems and the majority of smart phone devices to allow people to track their position no matter where on earth they happen to be. Short range wireless communication is used for transactions and passing data between handheld devices of all types. Two principle technologies exist for this, RFID and Bluetooth. As such, the growth in wireless technologies and their potential applications shows no signs of slowing down.