The British Isles ( , Ellanyn Goaldagh, Eileanan Breatannach, Ynysoedd Prydain) are a group of islands off the northwest coast of continental Europe comprising Great Britain, Ireland and a number of smaller islands. The term British Isles is controversial in relation to Ireland (see British Isles naming dispute) where its use is objected to by many people and by the government of the Republic of Ireland. Its use is also avoided in relations between the governments of the Republic of Ireland and the United Kingdom, who generally employ the term these islands.

There are two sovereign states located on the islands: the United Kingdom of Great Britain and Northern Ireland and Ireland (also described as the Republic of Ireland in cases of ambiguity). The group also includes the Crown dependencies of the Isle of Man and, by tradition, the Channel Islands, although the latter are not physically a part of the archipelago. There are other common uncertainties surrounding the extent, names and geographical elements of the island group.