Nickel silver is an alloy made from copper, nickel and zink.
Known in China for centuries, the production of nickel silver in Germany only begun in 1823 as a cheap substitute for real silver.
Nickel silver is harder than regular silver and is used for objects of daily use (e.g. cutlery) that were often silver-plated.
It has also a lot of technical applications. Instrument keys are usually made from nickel silver.