Finnish Sign Language (suomalainen viittomakieli in Finnish) is the sign language most commonly used in Finland. There are 5000 (estimate) Finnish deaf who have Finnish Sign Language as a mother tongue. Linguistically Finnish Sign Language is closest to Swedish Sign Language, from which it began to separate as an independent language in the middle of the 19th century.
Finnish legislation recognized Finnish Sign Language as one of Finland's domestic languages in 1995 when it was included in the renewed constitution. Finland then became the third country in the world to recognize a sign language as a natural language and the right to use it as a mother tongue.
Courses in "sign language" have been taught in Finland since the 1960s. At that time, instruction taught signs but followed Finnish word order (see Manually Coded Language). Later, as research on sign languages in general and Finnish Sign Language in particular determined that sign languages tend to have a very different grammar to oral languages, the teaching of Finnish Sign Language and "Signed Finnish" have diverged.
^a Sign-language names reflect the region of origin. Natural sign languages are not related to the spoken language used in the same region. For example, French Sign Language originated in France, but is not related to French.