The pied piper

Okay, everyone knows the story of the pied piper, the guy who played the flute in the german city of Hameln and all the rats followed him and all that…
but, being in germany, and visiting hameln it got me thinking, why is he called Pied in english? in german he’s called the Rattenfaenger or ratcatcher…
what does pied mean and why was he called it?

He is generally depicted as wearing a multi-colored outfit. The word Pied can mean multi-colored.