Is Sign Lanuage universal?
No, sign language is no more universal than spoken languages. American Sign Language (ASL) is used in the United States, most of Canada, and a few other countries with strong American influence. ASL has unique grammatical, lexical and linguistic features of its own and a unique vibrant culture. Part of the history of development of ASL is derived from French Sign Language (LSF). Various signed languages have evolved over the years and continue to do so just as spoken languages have evolved and continue to evolve. Even though roots of ASL are linked with LSF, the languages evolved differently and would not now be understood between a LSF signer and an ASL signer. The misconception among the general population in the US is that ASL is basically English on the hands. In addition, areas of the world use their own sign languages, such as England (British Sign Language) and Australia (Australian Sign Language).
Because ASL is not English, educators have developed a number of signed codes which use ASL vocabulary items, modify them to match English vocabulary, and put them together according to English grammatical rules. These codes have various names including Signed Exact English (SEE) and Manual Coded English (MCE). Additionally, when native speakers of English and native users of ASL try to communicate, the "language" that results is a mixture of both English and ASL vocabulary and grammar. This is referred to as PSE (Pidgin Signed English) or contact signing.