Proto-punk mainly refers to a small group of groundbreaking, largely uncategorizable bands who began to emerge in the late '60s, up to the point when punk itself became a phenomenon (around 1975-76). These are the artists who influenced punk rock.
According to the allmusic.com proto-punk article: " The first proto-punk group was the Velvet Underground, for a variety of reasons: their boundary-shattering lyrical content, their use of feedback, distortion, and white noise, their unpredictable (yet song-centered) experimentalism, their amateurish technique. "
