It's bias binding usually used for finishing seams.. I've used it for hems and dress necklines or armholes that I'm afraid will fray..
I'll be she thought you could use it to bind quilts, but I think those are too narrow. Ahh, the yellow one is a pre-made quilt binding.. so it's wider. still it's only one thickness and there's usually not enough to do a whole quilt in one packet....your call.