Measuring and sensing data provide us with information to make sound decisions in arenas as diverse as economics, ecology, security, and health. Did you know that sensors track elephant herds in Africa and refugee migration all over the world?

There are many different instruments to measure many different parameters. Thermometers measure temperature, radar guns measure the speed of passing cars, and global positioning satellite (GPS) receivers can determine your car’s exact position when you are lost in a new town.

Measuring and sensing devices are classified as either in-situ (in direct contact) or remote (not in direct contact) with regard to the medium or object they are measuring or sensing.

A dramatic example of the effect that sensing has on global ecology and economics was the use of satellite pictures to prove the extent of rain forest devastation over a decade. This critical evidence affected government plans and policies for rain forest burning, clearing, and settlement.