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, play or a performance to mark the sign of enjoyment and approval. Audience members clap their hands at random to produce a constant noise; however, it tends to synchronize naturally to a weak degree. 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.