Once you've finished a quilt and it's ready to be hung, you need to sew on a quilt sleeve. It's a long piece of fabric that can only be hand-sewn onto the back of the quilt* (if you sewed it on by machine before you quilt the whole thing, it would just get quilted over. I've thought about alternatives many times, and I feel like if someone could magically do mine, I could kiss them!).
*EDIT: Thanks to Ben and Meli who mentioned using a blind hem stitch to attach after the quilt is done - you can see a tutorial here by Lee Heinrich for Bernina. If you have the right equipment, this could work for you, too!
I find it a pain to do - mostly because you're dealing with large swathes of fabric, which you have to fashion into long tunnel-like contraptions, pin accurately to the quilt, and then hand sew. I'd much rather be working on another project! However, using Jacquie Gering's easy, picture-heavy quilt sleeve tutorial makes things a little easier.
Anyway, since I've sewn almost 20 quilt sleeves over the last month for my solo exhibition in March (phew, someone please get me some hand lotion and a glass of wine, stat), I've compiled a few pointers. I'm no expert but I hope these do help someone out there.