Welcome to Guernsey!
The Bailiwick of Guernsey (French: Guernesey, Guernesiais: Guernési, Sercquiais: Gyernëzi) is a group of islands in the English Channel, part of the Channel Islands. Guernsey itself is the main island, some 50 miles west of Normandy, it's about 6 miles long by 3 miles wide, with St Peter Port as its chief settlement.
In 1066 William Duke of Normandy gained the crown of England, so his descendants ruled many parts of France as well as ruling England. A series of wars, and peace treaties followed by more wars, wrested control of French territory away from England to the growing kingdom of France, until all that remained were the Channel Islands. And so they remain today. The Bailiwick of Guernsey, like that of Jersey, is therefore a "Crown Dependency". The Channel Islands are not subject to the UK parliament or legislation or - crucially - taxation in any way, but they cede control of defence and most international affairs to the UK. The rules of this arrangement are unwritten and all parties have shied away from testing them.
Guernsey grew up as a fishing port but from 1700 found that smuggling paid better, as mainland taxes rose sharply. Even more lucrative was piracy (illegal) and privateering (much the same thing, but legal if it was against the King's enemies). The islands were occasionally fought over (e.g. during the English Civil Wars), but more often they were heavily fortified against invasions that never came. One such phase was during the French Revolutionary and Napoleonic Wars, another was during the German occupation of the Second World War. So as they weren't attacked, the fortifications remain in good condition, and provide some of the main sights on Guernsey.
Post-war development was faltering: light industry, tomatoes & horticulture (undercut by the Dutch), and offshore finance (risky even when legitimate). Mass tourism never really started, and so Guernsey has concentrated on high-end tourism. Come here and feel like a swell.
The Bailiwick of Guernsey (French: Bailliage de Guernesey, Guernésiais: Bailliage dé Guernési) is one of three Crown Dependencies.
Separated from the Dukedom and Duchy of Normandy by and under the terms of the Treaty (or Peace) of Le Goulet in 1204, the Bailiwick comprises a number of islands in the English Channel which fall into three separate sub-jurisdictions: Guernsey, Alderney and Sark. Herm is administered as a part of Guernsey.
A bailiwick is a territory administered by a bailiff. The bailiff of Guernsey is the civil head and presiding officer of the States of Guernsey, but not of Alderney or Sark. He is the head of the judiciary of the Bailiwick.