Programming is a form of music production and performance using electronic devices, such as sequencers, to generate sounds of musical instruments. Programming is used in nearly all forms of electronic music and in most hip hop music since the 1990s. It is also frequently used in modern pop and rock music from various regions of the world, and sometimes in jazz and contemporary classical music. In the 21st century, programming has been incorporated into various styles of post-hardcore and metalcore music.