What is the one form of communication that is understood by every culture and in every country?
Sign language. Most societies on earth use sign language to
communicate. The American Sign Language is not known world wide,
but with the lack of communication barriers of language, it's one
of the most popular.
Music is considered to be the international language that unites
all nations. Good music, played well, tells the same stories in all
countries and all cultures. Music breaks down walls. On 29 Feb 2008
the New York Philharmonic Orchestra performed in Pyongyang, the
capitol of North Korea. Among other music they performed the Korean
national song and the US national anthem, The Star-Spangled Banner;
to rapturous applause. That's communication.