Hawkwind are an English rock band, one of the earliest space rock groups. Their lyrics favour urban and science fiction themes. They are considered a key link between the hippie and punk cultures. Hawkwind are primarily known for playing "space-rock", a hybrid of hard-rock and acid-rock that united the sonic power of the former and the free improvisation of the latter. Formed in November 1969, Hawkwind have gone through many incarnations and styles of music. Dozens of musicians, dancers and writers have worked with the group since their inception.