Carbon arc electrode
A carbon or graphite electrode used primarily for thermal cutting, gouging, or groove melting via an electric arc. It locally melts the material without experiencing significant self-consumption.
You mainly use carbon electrodes for arc welding when you want a filler-free weld or carburization. The arc burns between the electrode and the workpiece and melts the material locally. It's important not to press the electrode too hard into the weld pool, otherwise you'll draw carbon into the weld and make it hard and brittle. Also, be careful not to use too much current, otherwise the electrode will burn off quickly and you'll lose control of the heat input. To keep the weld clean and prevent distortion, it helps to clamp the workpiece well and not leave the heat in one spot for too long.