As the third most widely-used language, sign language is one the interesting languages to use. It has been used in some form in the U.S for over 200 years. I just recently joined a sign language club at my school because I wanted to know more about the language and learn how to sign.
Groups of deaf people have used sign languages throughout history. One of the earliest written records of a sign language is from the fifth century BC. Until the 19th century, most of what we know about historical sign language is limited to the manual alphabets (fingerspelling systems) that were invented to facilitate transfer of words from a spoken language to a sign language, rather than documentation of the language itself.
Sign languages generally do not have any linguistic relation to the spoken languages of the lands in which they arise. The correlation between sign and spoken languages is complex and varies depending on the country more than the spoken language. For example, the US, Canada, UK, Australia and New Zealand all have English as their dominant language, but American Sign Language (ASL), used in the US and most parts of Canada, is derived from French Sign Language. The other three countries sign dialects of British, Australian and New Zealand sign language. Similarly, the sign languages of Spain and Mexico are very different, despite Spanish being the national language in each country, and the sign language used in Bolivia is based on ASL rather than any sign language that is used in a Spanish-speaking country. Variations also arise within a 'national' sign language which don't necessarily correspond to dialect differences in the national spoken language; rather, they can usually be correlated to the geographic location of residential schools for the deaf.
In linguistic terms, sign languages are as rich and complex as any spoken language, despite the common misconception that they are not "real languages." Professional linguists have studied many sign languages and found that they exhibit the fundamental properties that exist in all languages.
Sign languages, like spoken languages, organize elementary, meaningless units into meaningful semantic units. This is often called duality of patterning. As in spoken languages, these meaningless units are represented as (combinations of) features, although often also crude distinctions are made in terms of hand shape, orientation, location, movement and Non-manual expression.
