What is a sacrificial anode, and what are its uses in engineering?
This is a technique used by engineers to prevent and control oxidation is exposed metal surfaces.
You build a bridge out of iron, and thermodynamics dictate that in a 1000 years, 10000 years, the iron will oxidize and the bridge will fall down. How to prevent damage in the short term? A good way is to attach a sacrificial anode to the metal surface, i.e. an anode made out of a metal that is more reactive than the metal you ar trying to protect.
So here you have made the metal you want to protect the CATHODE of an electrochemical cell. The typical metals used are aluminum or zinc or even magnesium. Of course you can replace the anode periodically; you cannot easily replace a corroded steel girder in a load bearing position.
See this site.