Why clouds next to songs?

I'm getting little cloud icons next to various songs. I have never enabled iMatch. There seems to be no

pattern to this. Among the clouded:

1) Songs I've uploaded through my own CD's

2) Songs I deleted some time ago have reappeared with clouds

3) "extra" versions of songs I already have...not exact duplicates...but the same song from a different album

4) Songs I never uploaded or downloaded or requested or whatever

How can I keep this from happening? All the clouds have a little download arrow in them. What's this even mean?

Carl