What does popularity on iTunes mean?

Related questions

1. Can I upload my music to iTunes?
2. Is there free music on iTunes?
3. How much does it cost to put a song on iTunes?
4. How do I put music on my iPhone without a computer?
5. Can you still buy songs on iTunes?
6. Do you get paid for podcasts on iTunes?
7. What is the number 1 selling song of all time?
8. What is considered the best song ever written?
9. Is Apple music the same thing as iTunes?
10. How long does it take for iTunes to approve a song?

Tags

1. #necessarily
2. #purchased
3. #album
4. #based
5. #itunes
6. #completely
7. #apple
8. #processes
9. #popularity
10. #sales
11. #internal
12. #doesn
13. #other
14. #calculated
15. #primarily
16. #track