How does electroless plating differ from electroplating?

The primary difference between electroplating and electroless plating lies in the mechanism used to deposit the metallic coating onto a surface.1

• Electroplating: This process is electrochemical. The object to be plated acts as the cathode in an electrolytic bath containing a solution of the metal salt. A low-voltage electrical current is passed through the solution, which drives the deposition of the metal onto the object.1
• Electroless Plating: This is a nonelectrical process that relies on controlled, autocatalytic (self-continuing) chemical reduction. Instead of using an external electrical current, the object is submerged in a chemical bath where the metal is deposited through a chemical reaction.21

While electroplating requires an electrical circuit, electroless plating is valued for its ability to produce uniform coatings on complex shapes and nonmetallic surfaces, such as plastics, which often require chemical pretreatment before the process begins.21