The linguistic heritage of the British Isles is rich, with twelve languages from six groups across four branches of the Indo-European family. The Insular Celtic languages of the Goidelic sub-group (Irish, Manx and Scottish Gaelic) and the Brittonic sub-group (Cornish, Welsh and Breton, spoken in north-western France) are the only remaining Celtic languages—the last of their continental relations becoming extinct before the 7th century. The Norman languages of Guernésiais, Jèrriais and Sarkese spoken in the Channel Islands are similar to French. A cant, called Shelta, is spoken by Irish Travellers, often as a means to conceal meaning from those outside the group. However, English, sometimes in the form of Scots, is the dominant language, with few monoglots remaining in the other languages of the region. The Norn language of Orkney and Shetland became extinct around 1880.

How many groups do these languages belong to?