iTunes will periodically send details about your song library to Apple servers. This feature is enabled by default and may be perceived as invasive by some users. Here are the instructions on how to opt out of this feature in
iTunes.
How To Prevent iTunes from Sharing Information About Your Library
Open
iTunes and sign in with your
Apple ID. Click on
Edit >
Preferences >
Store tab. Clear the
Share details about your library with Apple checkbox and click on
OK:
N.B. In doing so, you'll also disable the program's ability to automatically fetch missing album artwork.