Radiohead are regarded as being among the most fearlessly creative bands of their era, although they are not universally popular. In general, their music is more complex than that of other pop musicians, incorporating a wide range of influences across genres and time periods, but they identify with the punk and post-punk movements rather than with progressive rock.Radiohead have sometimes been cited as an "outsider" band within the mainstream, or vice versa. Some fans assume the band to be the natural inheritors of the mantle of R.E.M., Pink Floyd or even The Beatles, though Radiohead have not enjoyed the same commercial success as these groups; Pink Floyd's The Dark Side of the Moon has so far sold over 40 million copies worldwide, whereas Radiohead's much-acclaimed OK Computer has sold just over 8.4 million copies. However, reportedly members of these bands cited Radiohead numerous times as one of the greatest modern rock bands. Examples include Michael Stipe (at one point a quasi-mentor to Thom), who is a great fan of the band's work, and Paul McCartney, who lists them as one of his favourite acts.Thom Yorke and Jonny Greenwood are chiefly responsible for songwriting, with Yorke initiating a song and Greenwood developing it, though the entire band is often involved. They all contribute lyrical and artistic ideas to each step of writing and recording music.All five members are highly respected musicians. Jonny Greenwood in particular is an incredibly talented and versatile musician; he is currently the BBC's Composer in Residence and is adept at numerous instruments aside from the guitar, notably the Ondes Martenot, harmonica and many that have never been recorded. Ed O'Brien, apart from his normal duties as guitarist, is a gifted drummer as well.This versatility and openness in the band has grown more pronounced over time. In recent years, especially, band members have embraced less clearly defined roles in the band. For example, bassist Colin Greenwood wrote much of "Dollars & Cents", a track on Amnesiac, by playing string samples from Alice Coltrane's work on top of a simple bassline, inspiring his brother Jonny's subsequent arrangement. Yorke switched to bass guitar on the song "The National Anthem". During an average live show one can expect all of them, with the exception of drummer Phil Selway, to play an assortment of instruments.Producer Nigel Godrich has worked with the band since the recording of The Bends, where he assisted producer John Leckie. He has contributed significantly to their sound, and has often been dubbed the "sixth member" of the band. However, after 5 recorded LPs and numerous EPs with the band, he won't contribute to Radiohead's follow-up to Hail to the Thief. Graphic artist Stanley Donwood is another candidate for "sixth member". He originally met Yorke at the University of Exeter and has produced, with Yorke's help, all of the artwork for the band since their My Iron Lung EP. He also has a great deal of influence over the public image of the band and input into the themes and concepts of Yorke's lyrics. Yorke is always credited under an alias, usually "Tchock", "Tchocky", or "Dr. Tchock", when collaborating with Donwood. The two also created the band's official website together at Radiohead.com.Early influences include The Beatles, Cardiacs (whom the band supported early in their career), The Smiths, Elvis Costello, Joy Division, Pixies, Talking Heads, Pink Floyd, U2, Jeff Buckley, Big Star, King Crimson, Roxy Music, R.E.M., Queen, Nirvana and the Jam, among others. Later influences have included jazz musicians like Charles Mingus, Miles Davis, Ornette Coleman and Krautrock pioneers such as Kraftwerk, Neu! and Can, whose song "Thief" Radiohead have covered live. Electronic music artists like Aphex Twin, Squarepusher, and Autechre have also been cited as important influences on Kid A and Amnesiac.