SignWriting is a writing system which uses visual symbols to represent the handshapes, movements, and facial expressions of signed languages. It is an "alphabet" - a list of symbols used to write any signed language in the world.
The SignWriting alphabet can be compared to the alphabet we use to write English, the Roman alphabet. The Roman alphabet can be used to write many different spoken languages. While each language may add or subtract one or two symbols, the same basic symbols we use to write English are used to write Danish, German, French and Spanish. The Roman alphabet is international, but the languages it writes are not.
In the same way, the symbols in the SignWriting alphabet are international and can be used to write American Sign Language, Danish Sign Language, Norwegian Sign Language, British Sign Language, Dutch Sign Language - any signed language you choose.
SignWriting makes it possible to have books, newspapers, magazines, dictionaries, and literature written in signs. It can be used to teach signs and signed language grammar to beginning signers, or it can be used to teach other subjects, such as math, history, or English to skilled signers.