Mapquest Offers Free Basic Turn-by-Turn GPS On Your iPhone

GPS: Global Posting System: The Global Positioning System (GPS) is a satellite system (space-based) that provides geographical location and time information in all weather, anywhere on Earth where there is an unobstructed line of sight to four or more GPS satellites. It is maintained by the United States government and is freely accessible to anyone with a GPS receiver 

iPhone: iPhone: The iPhone is Apple's line of smartphones. That was also the original name of the first iPhone, which was announced on January 9th 2007 by Steve Jobs during the Macworld Keynote. The iPhone was released to the public in June of the same year. The development of the iPhone started in 2004, was internally called "project purple" and was the fruit of a collaboration between Apple and AT&T. Since then, Apple has released new iPhone models every year, with the iPhone 3G in July 2008, the iPhone 3GS in June 2009, the iPhone 4 in June 2010, the iPhone 4S in October 2011 and the iPhone 5 in September 2012. The iPhone represented more than half of Apple's revenues in 2012.