GPS

==GPS = Global Positioning System==
GPS shows positions on the Earth. 
== GIS = Geographic Information Systems ==
===GPS has three parts: the space segment, the user segment, and the control segment.===
The space segment consists of 24 satellites, each in its own orbit 11,000 nautical miles above the Earth. The user segment consists of ground stations (five of them, located around the world) that make sure the satellites are working properly. The GPS satellites each take 12 hours to orbit the Earth. Each satellite is equipped with an accurate clock that allows it to broadcast signals coupled with a precise time message. The ground unit receives the satellite signal, which travels at the speed of light. Even at this speed, the signal takes a measurable amount of time to reach the receiver. The difference between the time the signal is sent and the time it is received, multiplied by the speed of light, enables the receiver to calculate the distance to the satellite. 
To measure precise latitude, longitude, and altitude, the receiver measures the time it takes for the signals from four separate satellites to get to the receiver. The GPS system tells you your location anywhere on or above the Earth to within about 10 feet. Even greater accuracy, usually within less than three feet, can be obtained with corrections calculated by a GPS receiver at a known fixed location.
There are basically two types of GPS: a self-contained unit and a device that attaches to a laptop or handheld computer. 
However, even several of the self-contained units are capable of downloading and uploading data to a personal computer. 
GPS is an excellent device for orienteering, camping, and hiking units. 
Possible future applications include calculating running speeds, object trajectories, and energy expenditure. These data are then used for analysis of movement or physical activity.
==More insights== 
GIS and GPS provides a basic ingredient for significantly improving decision making. These tools involve the location, distribution, or impact of people, places, and events in the county and the world. Proximity of customers to a store location, the routing of emergency vehicles to an incident, and the change over time in a habitat all share the common component of geography.
Just about anyone or anything can be associated with a known location in the world; a street address, a service region, a climatic zone, a voting district or a latitude/longitude coordinate. Geographic information systems (GIS) software is the ideal tool for extracting the patterns and trends inherent in location-based information.
Geography is information about the earth's surface and the objects found on it, as well as a framework for organizing knowledge. GIS is a technology that manages, analyzes, and disseminates geographic knowledge.
Mapmaking and geographic analysis are not new, but GIS performs these tasks better and faster than do the old manual methods. And, before GIS technology, only a few people had the skills necessary to use geographic information to help with decision making and problem solving.
GIS engages and promotes critical thinking, integrated learning and analysis, and multiple intelligences and sciences at most levels. GIS technology is one of the hottest new tools in education and research. GIS is one of the fastest growing high-tech careers for students today. GIS training helps students develop computer literacy, analytical approaches to problem solving, and communication and presentation skills.
==Links==
===Grass===
* http://grass.itc.it/ uses open source technology
* Geographic Resources Analysis Support System, Commonly referred to as GRASS, this is a Geographic Information System (GIS) used for geospatial data management and analysis, image
processing, graphics/maps production, spatial modeling, and
visualization. GRASS is currently used in academic and commercial
settings around the world, as well as by many governmental agencies and
environmental consulting companies.
===Another GIS tool being developed===
* QGIS: http://qgis.org/content/view/24/104/