Guernsey is an island in the English Channel off the coast of Normandy that is part of the Bailiwick of Guernsey, a British Crown Dependency.

It is the second largest of the Channel Islands, an island group roughly north of Saint-Malo and the Cotentin Peninsula. The jurisdiction consists of ten parishes on the island of Guernsey, three other inhabited islands (Herm, Jethou and Lihou), and many small islets and rocks.

It is not part of the United Kingdom, although defence and some aspects of international relations are managed by the UK. Although the bailiwicks of Jersey and Guernsey are often referred to collectively as the Channel Islands, the "Channel Islands" are not a constitutional or political unit. Jersey has a separate relationship to the Crown from the other Crown dependencies of Guernsey and the Isle of Man, although all are held by the monarch of the United Kingdom.

The island has a mixed British-Norman culture, although British cultural influence is stronger, with English being the main language and the Pound sterling its primary currency. The island has a traditional local language known as Guernésiais.

Guernsey has been a tourist destination since at least the Victorian days, with the first tourist guide published in 1834. In the 19th century, two rail companies (London and South Western Railway and Great Western Railway) ran competing boats from the UK mainland to St Peter Port, with a race to the only convenient berth. This was halted with the sinking of the SS Stella in 1899.

Guernsey enters Britain in Bloom with St Martin Parish winning the small town category twice in 2006 and 2011, Saint Peter Port winning the large coastal category in 2014 and St Peter's winning the small coastal prize in 2015.

The military history of the island has left a number of fortifications, including Castle Cornet, Fort Grey. Guernsey loophole towers and a large collection of German fortifications with a number of museums.

The use of the roadstead in front of St Peter Port by over 100 cruise ships a year is bringing over 100,000 day-trip passengers to the island each year.