What exactly IS a quilt sandwich?

I just bet you have been wondering what in the world a quilt sandwich is.  Right???  If you've made a quilt you will know exactly what I mean.

Nope!  This is not it -- just your ordinary (except that I used crust for one piece) peanut butter and jelly sandwich.  Nothing fancy about this spring break lunch today!

A quilt sandwich is what you get when you put the backing fabric...

....together with the batting...

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....and, finally top with the pieced quilt!  Pin it all together, and you have a quilt sandwich!

Next up will be figuring out how to get this into the quilting frame.  It's an old one I bought at my favorite thrift store, and this will be my first try at using it.  Here goes....