Janszoon

I think there are two ways of using the word. One definition is what you just described whereby anyone who sells millions of albums is "pop". The other definition relates to pop as a genre. It's a style, usually with a heavy emphasis on vocals, rhythm and catchiness, that can be played by anyone regardless of whether they've sold millions of albums or not.

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A Night in the Life of the Invisible Man

Time & Place

25 Albums You Should Hear Before the Moon Crashes into the Earth and We All Die

last.fm