Jersey, officially the Bailiwick of Jersey, is a possession of the Crown in right of Jersey, off the coast of Normandy, France. Jersey was part of the Duchy of Normandy, whose dukes went on to become kings of England from 1066. After Normandy was lost by the kings of England in the thirteenth century, and the ducal title surrendered to France, Jersey and the other Channel Islands remained attached to the English crown. Nowadays, it's a self-governing parliamentary democracy under a constitutional monarchy.
Scholars variously surmise that Jersey and Jèrri derive from jarð (Old Norse for "earth") or jarl (earl), or perhaps a personal name, Geirr ("Geirr's Island"). The ending -ey denotes an island.
Thank you, Sabrina, for my very first postcard from Jersey and such a powerful stamp on the back!