Electrodes

I have never understood correctly what electrodes are.

Source: tatoeba (2756565)

An electrolysis is a passage of direct current through an ion-conducting solution, producing a chemical change at the electrodes.

Source: tatoeba (8767490)

Then a mild electrical current sent through electrodes on the volunteers’ scalp caused the brain to suppress signals that affect the inner ear.

Source: tatoeba (10954127)

Cheok said different tastes are triggered by molecules that cause chemical ionization on the surface of the tongue, sending the brain electrical signals of a specific amplitude and frequency that are possible to reproduce with two electrodes.

Source: tatoeba (11202380)