Answer by taking a quote from the following article:

The Dark Side of the Moon is the eighth studio album by English rock band Pink Floyd, released on 1 March 1973 by Harvest Records. The album built on ideas explored in earlier recordings and live shows, but lacks the extended instrumental excursions that characterised their earlier work. Its themes explore conflict, greed, the passage of time, and mental illness, the latter partly inspired by the deteriorating mental state of founding member and principal contributor, Syd Barrett. Developed during live performances, an early version was premiered several months before recording began; new material was recorded in two sessions in 1972 and 1973 at Abbey Road in London.

The Dark Side of the Moon became one of the best-selling albums of all time and is in the top 25 of a list of best-selling albums in the United States. Although it held the number one spot in the US for only a week, it remained in the Billboard album chart for 741 weeks. The album re-appeared on the Billboard charts with the introduction of the Top Pop Catalog Albums chart in May 1991, and has been a perennial feature since then. In the UK, it is the seventh-best-selling album of all time and the highest selling album never to reach number one.  In the US the LP was released before the introduction of platinum awards on 1 January 1976. It therefore held only a gold disc until 16 February 1990, when it was certified 11x platinum. On 4 June 1998 the Recording Industry Association of America (RIAA) certified the album 15x platinum, denoting sales of fifteen million in the United States - making it their biggest-selling work there (The Wall is 23x platinum, but as a double album this signifies sales of 11.5 million). "Money" has sold well as a single, and as with "Time", remains a radio favourite; in the US, for the year ending 20 April 2005, "Time" was played on 13,723 occasions, and "Money" on 13,731 occasions. Industry sources suggest that worldwide sales of the album total about 45 million. "On a slow week" between 8,000 and 9,000 copies are sold, and a total of 400,000 were sold in 2002, making it the 200th-best-selling album of that year - nearly three decades after its initial release. The album has sold 9,502,000 copies in the US since 1991 when Nielsen SoundScan began tracking sales for Billboard. To this day, it occupies a prominent spot on Billboard's Pop Catalog Chart. It reached number one when the 2003 hybrid CD/SACD edition was released and sold 800,000 copies in the US. On the week of 5 May 2006 The Dark Side of the Moon achieved a combined total of 1,716 weeks on the Billboard 200 and Pop Catalog charts. One in every fourteen people in the US under the age of 50 is estimated to own, or to have owned, a copy. Upon a chart rule change in 2009 allowing catalogue titles to re-enter the Billboard 200, The Dark Side of the Moon returned to the chart at number 189 on 12 December of that year for its 742nd charting week. It has continued to sporadically appear on the Billboard 200 since then, reaching 900 weeks on the chart in April 2015.  "The combination of words and music hit a peak," explained Gilmour. "All the music before had not had any great lyrical point to it. And this one was clear and concise. The cover was also right. I think it's become like a benevolent noose hanging behind us. Throughout our entire career, people have said we would never top the Dark Side record and tour. But The Wall earned more in dollar terms."

in what other countries did it sell
In the UK,