For the life of me, I don't get it...if you put a top on it, you would have to quilt through the layers, then you'd just have a mess on the back, right? What do you do with it?

Bags, casserole carriers, kitchen items, Christmas tree skirts, stockings, - it depends on the print.

Quick as a flash baby quilts? :)

They have been using pre-quilted fabric here in Japan for many years to make tote bags and floor cushion covers.

I used some to do tablerunners and placemats in the sew and flip method. When finished, I lifted the white pre-quilted thread and pulled it out until just my flip and sew stitches showed. I put a binding on it and you would never know it was pre-quilted fabric. I had a ton of it to use up and didn't like the look of the pre-quilted on my projects. Sounds crazy? then just use it for potholder, mug rugs and casserole dishes like someone mentioned.

Totes, Diaper bags

My mom's made purses out of it. She makes a knock-off of the Vera Bradley kind and this saves her from having to quilt the material first.

Ditto here.

OK !! I get it...pre-quilted fabric isn't generally used for quilts! LOL...no wonder I couldn't get it! I t makes sense for bags, totes and pot holders, etc...thanks all.

Exactly! Pillow shams, bassinet/baby basket sets, picnic blankets. Back with solids or flannels and SITD or tie at intervals (very easy, since the predone quilting is usually a grid- I do it with an isolated deco stitch like a heart, snowflake, leaf, etc. or a hand-stitched sashiko motif. If you want a thick quilt, quilt the top and a sturdy batting like W&N, then add the prequilted backing and tie discreetly. I only used prequilts when I found GORGEOUS batik ones or baby/kid/novelty ones that suit someone. Quick but nice gifts.