how have computers changed mapmaking in recent years? And What is the Global Positioning System?

http://en.wikipedia.org/wiki/Cartography#Technological_changes

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Computers have had a profound impact on mapmaking in recent years. They have revolutionized the way maps are created, updated, and accessed. Here are a few ways in which computers have changed mapmaking:

1. Digital Mapping: Computers have enabled the transition from traditional paper maps to digital maps. Mapmakers now use specialized software and Geographic Information Systems (GIS) to create and edit maps digitally. This has made the process more precise, efficient, and flexible.

2. Real-time Updates: With computers and the internet, maps can be updated in real-time. Mapmakers can easily incorporate the latest data, such as changes in road infrastructure, new landmarks, or updates from satellite imagery. This allows for more accurate and up-to-date maps.

3. Interactive and Customizable Maps: Computers have made it possible to create interactive and customizable maps. Online mapping platforms, like Google Maps, allow users to personalize their maps, choosing the layers of information they want to view, adding annotations, and customizing routes. This has empowered individuals and businesses to use maps in ways that suit their specific needs.

4. Satellites and Remote Sensing: Computers are crucial in processing and analyzing data collected by satellites and remote sensing technologies. Satellites equipped with advanced sensors capture high-quality images of Earth, which are then processed by computers to create detailed maps. This has greatly improved the accuracy and resolution of maps.

Now let's move to your second question:

The Global Positioning System (GPS) is a satellite-based navigation system that provides precise location information anywhere on Earth. It was developed and is maintained by the United States Department of Defense. The GPS system consists of a network of satellites in Earth's orbit and receivers on the ground. Here's how it works:

1. Satellites: The GPS system includes a constellation of 24 satellites orbiting the Earth. These satellites continuously transmit radio signals that contain information about their location and the time the signal was transmitted.

2. Receivers: GPS receivers, which can be found in smartphones, car navigation systems, or dedicated GPS devices, receive signals from multiple satellites simultaneously. The receiver calculates its distance from each satellite based on the time it took for the signals to travel.

3. Trilateration: Once the GPS receiver has received signals from at least four satellites, it uses a process called trilateration to determine its precise location. The receiver compares the time it took for each signal to arrive, which allows it to calculate the distance from each satellite.

4. Position Calculation: The GPS receiver combines the distance measurements from multiple satellites, along with the satellites' known locations, to calculate the user's exact position using mathematical algorithms.

The Global Positioning System has become an essential tool in various applications, including navigation, surveying, mapping, and tracking. It has revolutionized the way people navigate and has made accurate location information readily available to anyone with a GPS receiver.