Electrode, is a solid electric conductor that carries electric current into non-metallic solids, or liquids, or gases, or plasmas, or vacuums. In an electrochemical cell, reduction and oxidation reactions take place at the electrodes.

In case of electrochemical, the well itself acts as a large electrode, typically the anode. An electric current is passed through the electrode, which can drive various chemical reactions in the surrounding groundwater. One application is in-situ remediation of contaminated groundwater. By applying an electric current, contaminants can be oxidized or reduced, converting them into less harmful forms.