Remote Sensing Tutorial: "The Concept of Remote Sensing
If you have heard the term 'remote sensing' before you may have asked, 'what does it mean?' It's a rather simple, familiar activity that we all do as a matter of daily life, but that gets complicated when we increase the scale at which we observe. As you view the screen of your computer monitor, you are actively engaged in remote sensing.
Artist�s drawing shows two aspects of remote sensing: 1) an image acquired by a sensor is displayed on a monitor, and 2) the man viewing the console is in effect using his eyes to sense the screen at a distance - the human aspect of applying a sensing device.
A physical quantity (light) emanates from that screen, whose imaging electronics provides a source of radiation. The radiated light passes over a distance, and thus is 'remote' to some extent, until it encounters and is captured by a sensor (your eyes). Each eye sends a signal to a processor (your brain) which records the data and interprets this into information. Several of the human senses gather their awareness of the external world almost entirely by perceiving a variety of signals, either emitted or reflected, actively or passively, from objects that transmit this information in waves or pulses. Thus, one hears disturbances in the atmosphere carried as sound waves, experiences sensat"
courtsey: nasa website