Definitions of footprint:

• noun:   the area taken up by some object

  Example: "The computer had a desktop footprint of 10 by 16 inches"

• noun:   a mark of a foot or shoe on a surface

  Example: "The police made casts of the footprints in the soft earth outside the window"

• noun:   a trace suggesting that something was once present or felt or otherwise important

  Example: "The footprints of an earlier civilization"