Though the music varied widely between regions and artists, the post-punk movement has been characterized by its "conceptual assault" on rock conventions and rejection of aesthetics perceived of as traditionalist, hegemonic or rockist in favor of experimentation with production techniques and non-rock musical styles such as dub, electronic music, disco, noise, jazz, krautrock, world music and the avant-garde. As a movement, post-punk has been characterized by its conceptual assault on what conventions?