GPS, the initials for Global Positioning System, was technology that was originally developed for the US Armed Forces It is a United States global navigation satellite system, providing reliable positioning, navigation, and timing services for world wide users continually, regardless of the time and weather conditions anywhere on or near our planet. There are three part to the GPS system: twenty-four to thirty-two satellites in Medium Earth Orbit, four monitoring and control stations here on Earth, and the navigation devices, themselves. GPS satellites send signals from space that the GPS devices, or receivers use to provide three-dimensional location (latitude, longitude, and altitude), as well as the time. GPS is now a very widely used navigation aid around the world, and is also a very useful tool for map-making, scientific uses, tracking and surveillance, land surveying, commerce and hobbies. Furthermore, the very precise time reference is included in many applications like the study of earthquakes and for synchronizing the time on cellular networks. GPS has become indispensable for transportation systems globally, as a provider of navigation for aviation, ground, and maritime operations. GPS provides important location information for emergency services like search and rescue and disaster relief. GPS provides accurate time for everyday business and industrial functions, such as mobile phone operations, power grids and even banking. The accurate, free, and constantly reliable signal from GPS have increased both safety and production in many areas of activity around the globe. GPS units that used to be so expensive that only the military could use them have come way down in price over the years, and have gone WAY up in quality. Today, you can buy very reliable, light weight and ever portable GPS units manufactured in China for a fraction of what they cost only a few years ago, and with little of the bulk of originals. Because of trade regulations, the Chinese manufacturers and wholesalers cannot sell or recommend maps for the US market, but savvy users have quickly discovered that the IGo8 system as used in TomTom, Magellan and Route 66 works well on these Chinese GPS units, and, in fact, that the units work exceptionally well for the price. The Chinese manufacturers also are very helpful in providing support and excellent explanations of how to load the software, so these make a very good, reliable and economical choice for the average user.