Music is an art form and cultural activity whose medium is sound and silence, which exist in time. The common elements of music are pitch, rhythm, dynamics, and the sonic qualities of timbre and texture. Different styles or types of music may emphasize, de-emphasize or omit some of these elements. Music is performed with a vast range of instruments and vocal techniques ranging from singing to rapping; there are solely instrumental pieces, solely vocal pieces and pieces that combine singing and instruments. The creation, performance, significance, and even the definition of music vary according to culture and social context.