Acapella is a musical performance style where singers create vocal music without instrumental accompaniment. This form can include various genres, such as pop, classical, and jazz, and often features harmonies, melodies, and rhythms produced solely by the human voice. In acapella groups, singers may imitate instruments or use vocal techniques like beatboxing to enhance the performance. Popularized by groups like Pentatonix and shows like The Sing-Off, this style has gained widespread appeal, showcasing the versatility and creativity of vocalists.