What does it mean when a song is in a key?

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Tags

1. #major
2. #bassline
3. #notes
4. #fundamental
5. #based
6. #minor
7. #chords
8. #derived
9. #group
10. #means
11. #around
12. #seven
13. #played
14. #revolves
15. #scale
16. #making
17. #melody