Signs are composed of five basic parts: handshape, movement, location, orientation, and nonmanual signs (i.e. facial expressions). For signs to be formed correctly, they must follow the rules and norms associated with each of these components.

Sign languages develop naturally among members of the deaf community.

There are many different sign languages. Most often, these sign languages are categorized according to the country in which they are spoken.

For example, though Americans and the British speak similar versions of English, their sign languages are very different. American Sign Language was heavily influenced by French Sign Language. For many years, British Sign Language had developed independently.

Even within a country, there are variations according to region. These variations are normal and caused by a variety of factors. In some countries the variations can be very severe and in other countries, the differences can be more minor.

The differences between sign languages, however, are not as different as the differences between spoken languages. When deaf people meet from different countries, they usually can establish basic communication without too much trouble. This ease of communication has contributed to the sense of an international deaf community.

Some sign languages are legally recognized by their home countries. In Kenya's draft constitution, which was rejected in a 2005 referendum, Kenyan Sign Language was to be recognized as an official national language in Kenya.

Reference:

Valli, Clayton, Ceil Lucas, and Kristin J. Mulrooney. Linguistics of American Sign Language: An Introduction, Gallaudet University Press: 2005.