Cathode

A cathode is a type of electrode through which electrons move. Electrodes are an electrical conductor (usually a metal) that is connected to something that is not a metal. Electric current is a flow of charges through a conductor. There are two theories; one theory is conventional current flow and the other is actual current flow. The anode delivers conventional (or customary) current (which travels in the opposite direction as electrons) and the cathode receives that current. This means that electrons come out of the anode and electrons go into the cathode.  

This lets an electric current go into an electrical device such as a battery or other electrical cell. It can also end in a vacuum, like in a cathode ray tube. In this case, the electrons may go into open space.

In other words, a cathode is a positive electrode on a battery and a negative electrode on an electrolytic cell. Electric current is perceived as flowing in the opposite direction that the electrons are flowing. So electrons go into the + (positive) terminal of a battery, but electric current goes out. Electrons go into the + (positive) terminal of an electrolytic cell, but electric current goes out.

An electrode through which electrons flows out of the device is termed a cathode because it is negatively charged. A cathode is a negative electrode on a battery and a negative electrode on an electrolytic cell.

Related pages
Photocathode
Cold cathode

References
How to Define Anode and Cathode 

Category:Electronic components