Electroplating, also known as electrochemical deposition or electrodeposition, is a process for producing a metal coating on a solid substrate through the reduction of cations of that metal by means of a direct electric current. The part to be coated acts as the cathode (negative electrode) of an electrolytic cell; the electrolyte is a solution of a salt of the metal to be coated; and the anode (positive electrode) is usually either a block of that metal, or of some inert conductive material. The current is provided by an external power supply.

Electroplating is widely used in industry and decorative arts to improve the surface qualities of objects—such as resistance to abrasion and corrosion, lubricity, reflectivity, electrical conductivity, or appearance. It is used to build up thickness on undersized or worn-out parts, or to manufacture metal plates with complex shape, a process called electroforming. It is used to deposit copper and other conductors in forming printed circuit boards, and copper interconnects in integrated circuits. It is also used to purify metals such as copper.

The term "electroplating" may also be used occasionally for processes that use an electric current to achieve oxidation of anions on to a solid substrate, as in the formation of silver chloride on silver wire to make silver/silver-chloride (AgCl) electrodes.

Electropolishing, a process that uses an electric current to remove metal cations from the surface of a metal object, may be thought of as the opposite of electroplating.

Throwing power is an important parameter, which describes the uniformity of electroplating current (and of the electroplated thickness). It depends mostly on the composition and temperature of the electroplating solution. Those compositions/conditions, that favor secondary current distribution with a small dependence of current on voltage (i.e. with low transfer coefficients) have a higher (better) throwing power.