Cornish is a Celtic language closely related to Breton and Welsh spoken mainly in Cornwall (Kernow) and also by a few people in Australia and the USA. There are currently about 300 fluent speakers and many more people have some knowledge of the language.
The most popular versions of Cornish are currently Common Cornish and UCR, though other versions also have supporters. The differences between the various versions of Cornish are not huge and do not prevent speakers from communicating with one another.
Some families are now bringing up their children with Cornish as their first language. Cornish names are popular for children, pets, houses and boats. People are writing and performing songs and poetry in Cornish, and the language is taught in some schools and at the University of Exeter.
source
wikipedia.org,
omniglot.com,
evertype.com &
ethnologue.com