We, first of all, need to know what Sing Language is. Sign language combines manual language, body language, movements of hands and body and facial expressions to convey meaning, and so, to comunicate with other people.
In 1620, Juan Pablo Bonet, a Spanish priest known for his work education for the deaf, published a book called, 'Reduction of letters and art for teaching people to speak'. It brought about a way of using manual alphabet that would enable the deaf and dumb people to communicate.
Charles-Michel de L'Epee invented the sign language. He published an alphabet that was inspired from Bonet's work on sign language. The first school for the deaf and dumb was founded in 1755 in Paris by Abbe de L'Epee. The first permanent school for the deaf was founded in Hartford, Connecticut in 1817.
Since the early years of the development of sign language, finger spellings and distinct finger positions to represent different letters of the alphabet have always been a part of sign language. The origin of the sign language can be traced back to the initial years of the Christian era. Signs are not always used to represent letters or single words. They are often used to represent ideas. They are rich and complex and should not be mistaken as mere visual representations of the words. Sign languages are based on phonemes, which are built into meaningful units of expression.