French Sign Language ("langue des signes française" or LSF) is the national language of the Deaf in France and French-speaking parts of Switzerland.
LSF is related and partially ancestral to German Sign Language (DGS), Dutch Sign Language (NGT), Flemish Sign Language (VGT), Belgian-French Sign Language (LSFB), Irish Sign Language (ISL), American Sign Language (ASL), Quebec Sign Language (LSQ), and Russian Sign Language (RSL).
Old French Sign Language is the language of the Deaf community in the 18th century in Paris around the time of the establishment of the first deaf schools.
Wikipedia. "French Sign Language." https://en.wikipedia.org/wiki/French_Sign_Language