Remote sensing is the use of various technologies to make observations and measurements at a target that is usually at a distance or on a scale beyond those observable to the naked eye.
Remote sensing technologies include: LiDAR, radar, infrared radiation (IR), thermal, seismic, sonar, electric field sensing and GPS. Depending on what is being detected, these various sensors might be mounted to a satellite, airplane, boat, submarine or UAV drone or from another convenient observation point such as a building top.
The data gathered by remote sensing is used for a large and growing number of applications including cartography, resource exploration, atmospheric chemical measurements, healthcare monitoring, surveillance, navigation and GPS tracking.
Remote sensing can be conducted through passive or active sensing. In passive sensor technologies, an existing observable phenomenon, such as light from the sun, is captured by a sensor, which might be, for example, a charge-coupled device (CCD) camera mounted on a satellite. In active sensing, the device includes a transmitter that sends out a signal, a particular light wavelength or electrons to be bounced off the target, with data gathered by the sensor upon their reflection.
Remote sensing is one of the basic enabling technologies for the Internet of Things (IoT), in which almost any imaginable entity can be equipped with unique identifiers and the ability to transfer data over a network autonomously.