The maps that we use online work because of GIS.

A geographic information system (GIS) is a kind of computer system. It captures, stores ,and displays data about locations on Earth.

It can use and compare any information about a location. The location can be expressed in many different ways. Some examples are addresses or ZIP codes. Others are latitude and longitude. These are imaginary lines that appear on every map of Earth.

Lines of latitude run east-to-west. Lines of longitude run north-to-south. These lines are used to find any place on Earth.

GIS helps us find out how different bits of information relate to each other. It tells us about the landscape and people around us.

Data Capture
Data Formats
GIS data comes in many forms.

One example is cartographic data. This includes objects you might find on maps. Examples are rivers, roads, hills, and valleys.

Interpreting photographs is a big part of GIS. This involves photos that are taken from above. These images are then carefully studied.

Digital data can also be entered into GIS. For example, satellites collect computer data from above. This can show how land is used, such as the location of farms, towns, and forests.

Finally, GIS data can also be collected to compare populations of people. For example, imagine you had a list of everyone's age in your state. With GIS data, you could compare the ages of people in your city to those in other cities. It would be laid out on a single map.

Spatial Relationships
GIS technology can be used to show how two spaces are related. For example, GIS could show how close farms are to water. It can also show patterns of how land is used, like where parks and neighborhoods are located.

It can also show networks of lines on a map. A line on a map might stand for a road, river, or highway. With GIS layers, however, that road might show the boundary of a public park next to the river.

GIS must make information from many different maps and sources fit together on the same scale. A scale is the relationship between the distance on a map and the actual distance on Earth.

Earth is curved, like a globe. It is not flat, like a paper map or a screen.

Different maps have different projections. A projection is a way of moving information from Earth's curved surface to something flat. You cannot put a curved, three-dimensional shape onto a flat surface without stretching some parts.

A world map can show either the correct sizes of countries or their correct shapes. It cannot do both.

GIS takes data from maps that were made using different projections. It combines them so all the information can be displayed using one shared projection.

GIS Maps
Very different data can be entered in a GIS system. When it is combined, it can produce many kinds of individual maps.

A common use of GIS involves comparing Earth's features with human activity. It allows us to deeply examine a certain area. For example, GIS maps can display if buildings in an area are in danger of being flooded. Maps of a single city can show voting patterns of people there. It can also show the average amount of money made by different people in the city.

Researchers can also look at change over time with GIS technology. They can use pictures taken by satellites to study how ice sheets have moved or disappeared in the North Pole.

GIS technology sometimes allows users to get more information about specific areas on a map. For example, a user might click on a school on a map to find how many students go there.

It is also easy to update maps because of GIS technology. Any new data can simply be added. A new map can then be displayed immediately. In the past, maps had to be redrawn. This takes more time and money.

GIS Jobs
GIS technology is used in many jobs.

Businesses can use GIS to help them determine where to open a new store. Scientists use GIS to track the movement of animals.

Government officials use GIS to help plan their response to earthquakes or hurricanes. GIS maps can show what neighborhoods are most in danger or the closest emergency shelters.

Engineers might use GIS to develop road networks or train routes.

There is no limit to the kind of information that can be analyzed using GIS technology.