Applause (Latin applaudere, to strike upon, clap) is primarily the expression of approval by the act of clapping, or striking the palms of the hands together, in order to create noise.  Audiences usually applaud after a performance, such as a musical concert, speech, or play, as a sign of enjoyment and approval. In most countries audience members clap their hands at random to produce a constant noise. It tends to synchronize naturally to a weak degree; in Russia, Norway and many northern and eastern European countries synchronized clapping is more popular than random clapping. As a form of mass nonverbal communication, it is a simple indicator of the average relative opinion of the entire group; the louder and longer the noise, the stronger the sign of approval.