Remote sensing
Data acquisition
Image processing
  Colour composites
  Geometric corrections
  Radiometric corrections
  Contrast enhancement
  Filtering
  Classification
  Visual interpretation
  Post-classification
  Indices
  Principal Component Analysis
  Combination of images
  Geospatial maps
  Combination of images and other data: DEM and DTM
Radar
GIS
 
What is remote sensing?
 

Remote sensing is defined as a technique for getting information about objects by analysing data collected by instruments that were not in direct contact with the objects.

Strictly speaking, the snapshot taken of your dog in the backyard is an example of remote sensing.
In common practice, however, the term is reserved for observation of the Earth via instruments placed on board planes or satellites.