**What I do know: Normally, a band or a record-company publishes beside a new album some singles or maxis, to promote the album or the tour (in the cas of the Stones). For example, we had Steerts Of Love, Biggest Mistake and Rain Fall Down from Bigger Bang.
**What I don't know, Pt. I: I have seen also other singles in the internet like "Rough Jsutice" or from Bridges To Babylon "Flip The Switch", which you can't find in public sale. Where are they from? Radio stations? Promo, but for whom?
**What I don't know, Pt. II: In my big collection, I have a live-single from Flashpoint (Ruby Tuesday; I know, there exists also Jumping Jack Flash and Angie)...in 1991, when they were published, was it able, to buy them in normal stores, or were they for promo?
**What I know, Pt II: Here are a lot of people, who know the andwers. ;-)
Flip The Switch and Sparks will Fly are promos, somewhat hard to find at a decent price nowadays. From Flashpoint, the most rare single would be PIB, wich have the same cover as Ruby Tuesday. Available as CD and vinyl. Early CD-singles from the Steel Wheels era can also be hard to find today, at decent prices. Me and my fellow Stonesviking JanRichards have an ongoing project were we try to track down ALL CD-singles, including promos, from the whole world. If someone has good info about different releases, we would be very interested. Up till now we identified a couple of hundred different CD-singlereleases.
Yes, apart regular singles bands release promo versions which are not availbe at stores and they for exclusive use for press or radio. Sometimes they have only one track, sometimes there is one track in several different versions (edited, remixed etc.), sometimes there are some bonus tracks. General rule is that if you can buy it in store it's a single, not a promo. If you hear it on the radio you can susprect that it's form the promo. If you don't know wheter the CD you have is regular one or promo check the linear notes. Promos have written on the cover something like "for promotional use only, not for sale" etc.