Some metals are electroplated to reduce dissolved metal cations so that they form a coherent metal coating on an electrode. Electrodeposition is the process used in electroplating. The most common surfaces that are plated are metals and plastics. Go to http://www.hitechplatingtinning.com/plating-materials/ for details.
Base metals like steel rust easily but are cheap and strong. Plating metals like chrome and zinc do not rust (or at least don't corrode) but are more expensive and/or not as strong. Plating gives us the best of both.