Are All iTunes from CDs?

I was looking through iTunes and came across some songs that I know were never issued in CD form.

So it got me to thinking does somenoe at iTunes simply play a good copy of a record and record it in mp3 format? Or does the label that issued the original record give iTunes the master to record?

What’s the SD with them?

I know that CDBaby does the MP3 encoding for tracks which they sell. That way they can ensure that the MP3 encoding is done to their standards. You supply the tracks in CD format. Note that this doesn’t mean you have to create physical CDs - you just create tracks that could be put on CDs.

I imagine that Apple does the same so that they can add their proprietary DRM (Digital Rights Management) and, like CDBaby, for quality control.