Its cover, which features a ray of white light going through a prism, is also one of the most famous album covers of all time. Analysts say that statistically, "Dark Side Of The Moon" is always playing somewhere on planet Earth. It is one of the most famous concept albums (albums where all the songs are about a central theme. Some concept albums tell a specific story), and used to be the best-selling album of all time. There is an album-pressing plant in Germany that does nothing but create copies of "Dark Side Of The Moon".