This paper presents the general features of parameter sensitivity maps and illustrates their practical use. We define parameter sensitivity maps as geoelectric responses in the measuring plane (at the surface) due to an elementary cube within the subsurface at three different depths. Responses of the three component as well as the total response of electrical dipoles formed on opposite cube surfaces are shown. In this paper we present such maps for 14 various linear electrode arrays. This paper is followed by an accompanying one about nonlinear and focussed arrays. Parameter sensitivity maps in these two papers provide a compact characterization of all known geoelectric arrays. We give several examples how to use them in planning and interpretation of field measurements.