An electrode is a coated metal wire used in welding. There are consumable electrodes that are consumed during welding like in stick welding, and non-consumable electrodes like in TIG welding. The numbers and letters on electrodes indicate properties like tensile strength and position used. Electrodes are classified as basic, cellulosic, rutile, or high iron powder based on coating composition and intended use. Basic electrodes require baking and provide high strength welds. Cellulosic electrodes do not require baking but produce higher hydrogen welds. Rutile electrodes are for general fabrication and baking is optional. Electrodes must be baked if exposed to air beyond specifications to remove moisture.