It is important to understand how a remote sensing tool operates in order to appreciate its ability to detect features - such as habitats - on the seabed (in intertidal or subtidal areas). There are many excellent texts and websites explaining all the technical aspects of remote sensing; for example Green et al., describe the use of satellite and airborne remote sensors for marine mapping in tropical waters. The following text is based on information available on the US NASA website with some definitions taken from Wikipedia.