Could someone esplain to me what is a smoke ring?

Smoke ring is the pinkish-red ring that seems to penetrate about 1/8 - 3/8 inch (or more) on smoked meats. Has more to do with looks than taste. Some think it's a must for real Q. Do a search on "smoke ring" and you find several threads on the subject.

Look in the link at the top of this page marked "smokin okie's barbecue guide" click on the brisket 101 and scroll down to some of the finished pictures. You can see it there.

Fresno

Here's a good thread I posted, with photos:

Smoke ring -- the Real Story